Yoshis (referred to as Yoshisaurs in the Super Mario World cartoon) are a sentient species of dinosaur that first appeared in Super Mario World. They later starred in Super Mario World 2: Yoshi's Island, Yoshi's Story, Yoshi Touch & Go, and Yoshi's Island DS. The name is derived from the Japanese interjection "yoshi!", meaning "great". Its pluralization has been a topic of some debate, with Nintendo of America has used both "Yoshies" and "Yoshis" in the Super Nintendo and Game Boy Advance versions of Yoshi's Island, respectively. Because the original Japanese has no plural marker, "Yoshi" is another possibility. The most well-known Yoshi is simply named Yoshi, and is an ally of Mario, often aiding Mario out or being a protagonist of his own adventures.
Yoshis are characterized primarily by their production and use of eggs as offensive tools. Regardless of gender, Yoshis can spontaneously lay hollow eggs after eating other animals or fruit, and then use them as projectile weaponry; other eggs have been shown to hatch into items, and some eggs hatch into baby Yoshis, as would be expected. In the Super Smash Bros. series, Yoshi is able to turn himself into an egg to either protect himself or to roll into others as an attack. Yoshis come in a variety of colours, although green is the most common (and is in fact the colour of the Yoshi character). Yoshis are most closely associated with Yoshi's Island, however they are a widespread species, found on a number of other islands, such as Lavalava Island and Isle Delfino, as well as the continental Mushroom Kingdom and the neighbouring Beanbean Kingdom.
Super Mario series
Super Mario World
Yoshis were first introduced in Super Mario World. Some Yoshis had been kidnapped by Bowser and his children during their invasion of Dinosaur Land. They had to be rescued by Mario and his brother Luigi, with help from their friend Yoshi.
Other green Yoshis, as well as red, yellow, and blue Yoshis can be found in the Star World. Eating Koopa shells gives Yoshis different abilities: after eating a red shell, the Yoshi would spit out a fireball, while yellow shells would make it heavy enough to shake the ground each time it lands a jump, and blue shells cause the Yoshi to grow wings and fly. Red, yellow and blue Yoshis experience the effect of the corresponding shell colour regardless of the colour of the shell they themselves were holding in their mouth. The rainbow shells of a Kamikaze Koopa grant all three special effects, while green shells yield no extra abilities, and could merely be spat out as a ricocheting projectile. If the Yoshi holds the shell in its mouth for too long, it swallows it. Yoshis can also eat other enemies as well as berries that grow on bushes in certain areas; eating ten berries causes the Yoshi to lay an egg that hatches into a Super Mushroom.
If the Yoshi gets hurt by an enemy, it will drop Mario and run around in a panic until Mario jumps back on its saddle.
Super Mario Sunshine
Yoshis play a major role in Super Mario Sunshine, acting as transportation for Mario proving themselves to be the key to obtaining several Shine Sprites. Yoshis normally appear in three different colors depending on what they eat: orange, pink, and purple. To get a Yoshi, Mario must first find a Yoshi Egg and give it the specific fruit it wants. Then the Yoshi will hatch and Mario can ride him. Each color of a Yoshi is also given the ability to spit different colored juice (this ability replaces the function of F.L.U.D.D.) that affects enemies in different ways. The orange juice can turn enemies into orange hovering blocks that disappear after a short amount of time, while the purple and pink juices make a similar block of the corresponding color but move vertically or horizontally depending on the color. Unlike F.L.U.D.D., Yoshi can also destroy the orange oozy graffiti.
If a Yoshi falls into water or runs out of juice (which depletes as time goes on and as the Yoshi sprays it), it will turn green and spit water instead of juice for a few seconds, before vanishing altogether.
New Super Mario Bros.
Yoshi, along with a red, a yellow and a blue Yoshi, appeared in some of the minigames in New Super Mario Bros.
New Super Mario Bros. Wii
Yellow, light blue, and pink Yoshis appear alongside the green Yoshi in New Super Mario Bros. Wii, where they aided Mario, Luigi and a pair of Toads save Princess Peach from Bowser. Red and blue Yoshis were originally going to appear in New Super Mario Bros. Wii, but they were replaced by the pink and light blue Yoshis for the final game.
In this game, the Yoshis can flutter jump and stomp enemies that Mario and the others couldn't normally defeat with jumps. Like in Super Mario World, the Yoshis main ability is how they can eat enemies, but they can't swallow shelled enemies at all, and the shells yield no special powers when held in the Yoshis' mouths. Instead, eating Venus Fire Trap allows the Yoshi to spit a fireball afterwards, and they can also fire ice balls and hammers right back at the enemies that threw them. Eating five berries and leaf-covered Pokeys causes Yoshis to lay eggs that hatch into useful items for the Mario Bros. and the Toads. When harmed, the Yoshi throws off its rider and runs around in a panic until someone jumps back on its saddle. Yoshis first appear in level 1-3.
Super Mario Galaxy 2
In Super Mario Galaxy 2, in Yoshi Star Galaxy Mario meets Yoshi a in later galaxies, meets others. Yoshis get power-ups such as the Dash Pepper, Blimp Fruit, and Bulb Berry. Yoshi also appears in Bowser's Galaxy Generator and waves to Mario as he goes to battle Bowser.
New Super Mario Bros. U
In New Super Mario Bros. U, Yoshis appear in a green color only, and they behave exactly like in New Super Mario Bros. Wii. Baby Yoshis also appear on the world map and certain levels and have 3 different colours with different abilities. Bubble Baby Yoshis are blue and spit out bubbles when the remote is shaken. Balloon Baby Yoshi is a magenta color that inflates like a balloon when the remote is shaken. Glowing Baby Yoshis appear as golden in color, and can illuminate the dark and stun enemies when the remote is shaken. Baby Yoshis are also vital in a new Toad House minigame. A new red meter appears when Yoshi eats Berries, which shows how many Berries Yoshi has eaten, effectively replacing the number system introduced in the game.
Super Mario Adventures
In Nintendo Power's Super Mario Adventures comics, which is loosely based on the Super Mario World video game, Bowser kidnaps various Yoshis from the Yoshi Village and their leader, Yoshi himself, has to team up with Mario and Luigi to save them and Princess Peach. Eventually they are able to free the Yoshis and have them stampede the wedding between Bowser and the brainwashed Peach, thus rescuing the princess. Bowser tries to hide in the giant wedding cake, but Mario has the Yoshis eat it, thus uncovering him and forcing him to accept defeat and leave Dinosaur Land.
Incidentally, their language was shown to consist of nothing but the word "Yoshi" in this depiction of Yoshi and his species, making it unintelligible to Mario and Luigi.
Yoshi appeared in various issues of the Nintendo-based German Club Nintendo comics. Other Yoshis also appeared in a few issues:
In the first game of the Yoshi series, Mario has to arrange egg halves and enemies to produce Small, Tall, Winged, and Star Yoshis. To get a Small Yoshi, Mario must combine two halves of a Yoshi egg. To get a Tall Yoshi, Mario must have one to four enemies in between the two halves of an egg. To get a Winged Yoshi, Mario must have five or six enemies in between the two halves of an egg. To get a Star Yoshi, Mario must have seven enemies in between the two halves of an egg. If a Small Yoshi hatches, 50 points are awarded. If a Tall Yoshi hatches, 100-250 points are awarded. If a Winged Yoshi hatches, 300-350 points are awarded. If a Star Yoshi hatches, 500 points are awarded.
Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
Super Mario World 2: Yoshi's Island is set long before Super Mario World and tells the story of Mario and Luigi's first days of life. Baby Bowser's caretaker Kamek had predicted that the two babies born that morning spelled disaster for the Koopas and attempted to kidnap them before the Stork could deliver them to their parents. However, he only manages to snag Baby Luigi, while Baby Mario falls to Yoshi's Island and lands unscathed on Yoshi's back.
The infant causes some brief panic amongst the Yoshi community, until Yoshi takes charge and decides to help reunite Mario and Luigi and send them to their parents. The other Yoshis agree to help him transport Baby Mario across Yoshi's Island to Bowser's Castle through use of a relay system. Each Yoshi carries the baby for one level in each world, before passing him on to the next Yoshi in line. To defend him against Kamek's forces and the hostile wildlife of the island, the Yoshis eat enemies, turning them into eggs which they can then throw at other enemies and obstacles. The Yoshis can also transform themselves into various vehicles through the use of Morph Bubbles, which helps them progress through the island. Eventually, Yoshi defeats Baby Bowser and forces Kamek to retreat, allowing him to rescue Baby Luigi and the Stork. The Yoshis then send them on their way to Mario and Luigi's parents.
In Yoshi's Story, Baby Bowser steals the Super Happy Tree, the source of the island's happiness, and transforms it into a storybook. He curses the Yoshis, making them unable to stop him. However, the curse does not affect six baby Yoshis in their eggs. When they hatch, the six Baby Yoshis decide to find the Super Happy Tree to refill the island with happiness.
The Yoshis travel across the island, eating fruits to boost their own happiness levels. As their collective happiness increases, more and more worlds become available to the Yoshis. Eventually, the Baby Yoshis reach Baby Bowser's Castle where they defeat Baby Bowser and reclaim the Super Happy Tree.
In Yoshi Topsy-Turvy (also known as Yoshi's Universal Gravitation) Yoshi's Island has once again been turned into a storybook, but this time, a spirit named Hongo is responsible. He did this to contain Bowser's trouble-making, but agrees that if Yoshi can subdue Bowser, he will restore the island.
Yoshi Touch & Go
In Yoshi Touch & Go, the Yoshis have to transport Baby Mario to the Stork after Kamek kidnapped Baby Luigi and caused the bird to drop Mario. The colour of the Yoshi varies depending on how many coins the player collects while guiding Baby Mario down to the ground. No further plot or background story is revealed.
Yoshi's Island DS
In Yoshi's Island DS, Bowser and Kamek travel back in time to kidnap seven star children in order to use the energy within their bodies to let Bowser take over the world. Since they don't know the identity of the children, they endeavor to kidnap every single infant in the Mushroom World, but one way or another, their quarry escapes their clutches. Only one child, a baby Yoshi, is not involved at all (although it is possible that the baby is Yoshi himself, who is now grown up); Baby Luigi is successfully captured, but manages to avoid detection for the duration of his imprisonment, and all the other children escape or are cast out by the villains, and help the Yoshis save the rest of the babies.
The gameplay is similar to the original Super Mario World 2: Yoshi's Island, although different babies have skills that help the Yoshis. With Baby Mario, Yoshis can dash around quickly and their eggs bounce off walls. With Baby Peach, they can flutter higher and catch winds with her parasol. Baby Donkey Kong can climb vines, carrying his Yoshi steed with him, and eggs thrown while he is present create small explosions when they hit. Baby Wario can collect coins and move metal objects with his magnet and Yoshis' eggs bounce. Finally, while Baby Bowser's weight means the Yoshi carrying him cannot eat enemies and make eggs, his fireballs can be used to defeat enemies and clear obstacles. A Yoshi can exchange the baby it is carrying for a different baby by visiting a Stork Stop, where the bird will bring in the new child and depart with the original one. Not all babies are available in all areas, however.
In the final battle, Yoshi and three others fight Bowser, carrying babies Mario, Peach, DK and Wario (Baby Bowser turned traitor when they reached Bowser's Castle). After their defeat, the Koopas return to the future and the babies are brought home by the Storks.
Super Mario RPG: Legend of the Seven Stars
In Super Mario RPG: Legend of the Seven Stars Mario and his partners visit Yo'ster Isle, where Yoshis race each other for sport in a competition known as the Mushroom Derby. Unfortunately, the last winner of the derby was an arrogant Yoshi named Boshi who proceeded to name himself leader of Yo'ster Isle and suspend the races. Instead, only one-on-one races between himself and slower Yoshis were allowed, with Yoshi Cookies as the prize. When Mario arrives, he helps Yoshi defeat Boshi in a race, prompting the people to try and appoint Yoshi as their new leader. Yoshi declines the offer, however, and instead has the Mushroom Derby re-opened to everyone, with no Yoshi in charge.
During the game, Yoshi also serves as a translator between Mario and the Yoshis, who speak their own language.
Super Smash Bros. series
Yoshi appears as a playable character in all the Super Smash Bros. series titles, in which he has various alternate colors, in addition to the basic green: red, blue, yellow, pink, light blue, purple, and black. Some stages and events involve fighting multiple Yoshis. In Super Smash Bros., only four of the eight Yoshi colors were playable; green, red, light blue, and yellow. The first six Yoshi colors were used in the computer-controlled Yoshi team battled during the 1-Player mode, and they all became playable in Super Smash Bros. Melee and Super Smash Bros. Brawl.
Paper Mario series
Mario and his partners visit a Yoshi Village on Lavalava Island during the events of Paper Mario. They were there looking for a Star Spirit that Bowser had trapped in a playing card and given to a minion to guard within the island's volcano, but they find they can't get into the mountain on their own. The Yoshi Village Leader says he'll help Mario and the others if they help round up five missing Yoshi Kids. With the help of their Cheep-Cheep babysitter, Sushie, Mario and co. soon find the young Yoshis and can continue on with their quest.
Paper Mario: The Thousand-Year Door
When Mario and his current set of partners visit Glitzville in Paper Mario: The Thousand-Year Door, they soon find themselves with custody of a Yoshi egg, after its initial owner, a hotdog vendor, decided against cooking and serving it once he realized it could move on its own accord. For a while, the egg follows Mario and his partners. Then, after the match with the Armored Harriers, Mario returns to find that the egg had hatched into a baby Yoshi, the colour of whom varies depending on how much time had passed between Mario's acquisition of the egg and its hatching. Mario names the Yoshi, who then travels with him and the other partners for the remainder of the game, before becoming a fighter at the Glitz Pit after the quest is over.
Mario & Luigi series
Mario & Luigi: Superstar Saga
This game shows that Yoshis also live in the Beanbean Kingdom. They are found at Yoshi Theater and Mario and Luigi must find Bean Fruit for seven hungry Yoshis to earn Neon Eggs and ultimately a Beanstar piece. They can be seen in the credits in Yoshi Theater watching the events of this game as well.
Mario & Luigi: Partners in Time
In Mario & Luigi: Partners in Time, the invading aliens known as the Shroobs deposit what appears to be a giant Yoshi Egg on Yoshi's Island. It swiftly becomes a tourist attraction, but eventually hatches into a monster known as Yoob, which proceeds to eat every Yoshi it can catch. A factory in its belly then encases the eaten Yoshis in Yoob Eggs, so that they will also hatch as monsters and help wreak havoc on the world. Fortunately, the plan is foiled by Yoshi, aided by Baby Mario, Baby Luigi and the adult Mario and Luigi, who had both traveled back in time to save Peach and stop the aliens. Yoshi discovers a way to escape through Yoob's digestive tract and the four Mario Bros. liberate the captured and imprisoned Yoshis to help him. They also defeat the guardian of the factory, Sunnycide, and once the Yoshis escape and the factory is destroyed, Yoob falls asleep.
Mario & Luigi: Bowser's Inside Story
Yoshi noises were seen in the code of Mario & Luigi: Bowser's Inside Story but unused. It is unknown if Yoshis themselves were going to appear in the game or it was left over from Partners in Time (as the game's engine was based off this game's). During one of the Fawful Guys' attacks, a roar very similar to Yoob's can be heard. In the attack, a long tongue (presumably belonging to a Fawfulized Yoshi) turns them into an egg and spits them out. This is a reference to Super Mario World 2: Yoshi's Island.
Mario & Luigi: Dream Team
Yoshis appear in Mario & Luigi: Dream Team as one of the many species invited to Pi'illo Island. Many Yoshis can be seen in various places such as Pi'illo Castle, Mushrise Park and Wakeport. There are many green, red, blue, aqua green, pink, light blue, grey and yellow Yoshis.
Mario & Sonic at the London 2012 Olympic Games
In Mario & Sonic at the London 2012 Olympic Games, Yoshis serve as the main objective in Dream Equestrian, where players must race to the finish line, carrying a wagon full of seven color Yoshi eggs. The eggs will hatch into Yoshis upon reaching the goal.
Mario Tennis Open
Most of the colored Yoshis (excluding the Purple, Orange, and Brown varieties) make an appearance in Mario Tennis Open, as downloadable QR characters. The different colors, and their playing types, are listed below.
Mario Kart 8
In Mario Kart 8, Yoshis can be seen as spectators in the following courses: Sweet Sweet Canyon (possibly referencing their large appetites and bright colors) Mount Wario, GBA Mario Circuit, SNES Donut Plains 3, N64 Yoshi Valley, and GCN Yoshi Circuit. Eight color variants also automatically unlock when both downloadable content packs are purchased, along with eight variants of Shy Guy.
Other appearances and references
The character Yoshi appears in many Mario games, including Yoshi's Safari, Super Mario 64, Super Mario Galaxy 2, and all the Mario Party, Mario Kart and Mario sports games. Other Yoshis have occasionally appeared in these games, including a pair in Mario Party, and aforementioned Yoshis in Mario & Sonic at the London 2012 Olympic Games. Yoshi's Rolling Egg Return Defensive Power Shot in Mario Power Tennis also has him changing to various different colours, although it it still the same, solitary character.
In the Super Mario All-Stars and Super Mario Advance 4 adaptations of Super Mario Bros. 3, the king in the castle of World seven is transformed into a green Yoshi by Ludwig von Koopa (whereas in the NES version of the game, predating Yoshis, the king was transformed into a Piranha Plant).
In Super Mario Chess, Yoshis appear as knights on Mario's team.
In addition, many Yoshi-themed Mario Kart racecourses have appeared: Mario Kart 64 has Yoshi Valley, Mario Kart: Super Circuit has Yoshi Desert, Mario Kart: Double Dash!! has Yoshi Circuit, Mario Kart DS has Yoshi Falls and reuses the GameCube course Yoshi Circuit, Mario Kart Arcade GP 2 has a two-course Yoshi stage, and while it doesn't introduce a new course, Mario Kart Wii reuses Yoshi Falls from the DS title. Yoshis also spectate a few courses in Mario Kart 8.
Although Yoshis don't appear in Super Paper Mario, a stone statue of one appears in Chapter 5: Land of the Cragnons. There is also a Sammer Guy called "Belly of the Yoshi" which may also be a reference to Yoob or how Yoshis can eat any amount of food without getting full. Yoshis were also referenced in Super Mario Galaxy by a planet shaped like a Yoshi Egg in the Good Egg Galaxy and by a planet shaped like a Yoshi head in the Space Junk Galaxy.
Yoshis were initially portrayed with long necks and small hands with three digits, although their design has since changed to make them more anthropogenic, with upright postures, shorter necks and grasping, human-like, four-digit hands. Additionally, Yoshis were originally conceived of as a type of Koopa, with the saddles on their backs being their shells. In addition, it is seen that Kamek and King Bowser live with many other Koopas on an opposite of sorts to Yoshi's Island after World 5 of Super Mario Advance 2 is cleared. Although most Yoshis have never been seen without their shoes, the appearance of Boshi in Super Mario RPG: Legend of the Seven Stars confirms that Yoshis have three toes on each foot, and also have white pads on the bottom of their feet.
A Yoshi's physical appearance changes depending how old they are. For example, in Paper Mario: The Thousand-Year Door, the Yoshi appears much smaller compared to other Yoshis. He also has hair, while most other Yoshis do not, though this is most likely to differentiate the character as playable. Newly-hatched baby Yoshis featured in Super Mario World (among other games) are both smaller and also proportioned differently than the adults, with short, stubby bodies lacking in saddles, almost no neck, and a slightly down-curved snout. After eating enough enemies, food or Power-Ups, these baby Yoshis will undergo a rapid growth spurt and look like adults from that point onward.
Yoshis come in a variety of colors. In Super Mario Sunshine they can even change skin color by eating different fruit, while their colors are determined by hatching time in Paper Mario: The Thousand-Year Door. Shoes' color is also usually in conjunction with skin color: a green Yoshi has red shoes, a red Yoshi has blue shoes, etc. This shoe color denomination was not set up until Yoshi's Story.
In Super Mario World, Yoshis had abilities depending on their color and Koopa Shells. If a blue Yoshi licks up a Koopa Shell, it could temporarily grow wings until it is swallowed or spit out. If a red Yoshi licks up a Koopa Shell, it could spit it back out as a trio of fireballs. If a yellow Yoshi licks up a shell, it can cause Ground Pounds for as long as it holds the shell in its mouth. Shells of the corresponding colours would also create those effects in a Yoshi of any colour.
This is all the (known) colors for a Yoshi and the first appearance of said color of Yoshi:
Yoshis are especially known for their long tongues that cling to most enemies, allowing a Yoshi to swallow it whole, although they do have teeth. They can either swallow whatever they eat, or encase it in an egg. The eggs can then be used as projectile weapons to defeat other enemies and bosses, while other eggs hatch into useful items like 1-Up Mushrooms. Yoshis also presumably have strong and efficient digestive systems, which digest live enemies very quickly, although in Super Mario World it would take a few minutes for a Yoshi to be able to swallow a Koopa Shell, and as discussed in the previous section, the shell grants the Yoshi special abilities in the meantime.
Yoshis have large snouts which they can use to sniff out fruit or other secrets that can be buried underground, although this feature is shown only in Yoshi's Story.
Most games show that Yoshis can swim, although how well they swim varies. In Super Mario World, they can swim and dive, although in Yoshi's Island DS, they cannot dive without the Submarine powerup. Yoshi also cannot dive in Super Mario Galaxy 2, although he can swim. In Super Mario Sunshine, Yoshis that live on or around Isle Delfino turn green and disappear if they touch water.
As discussed earlier, in Super Mario World, when carrying a yellow Koopa Shell in their mouths (or any shell if the Yoshi itself is yellow), the Yoshi becomes heavy and shakes the ground each time it lands after a jump or fall. Yoshis were also one of the first creatures shown performing proper Ground Pound attacks - a move in which the performer jumps into the air, flips and then slams into the ground. Yoshis first performed the move in Super Mario World 2: Yoshi's Island. Yoshi uses "Ground Pound" in the Super Smash Bros. series as a special attack. Bowser was shown doing the equivalent of a Ground Pound in Super Mario Bros. 3 (before the debut of Yoshis), and in games since then. Other characters have also been shown Ground Pounding, including Mario himself in titles such as Super Mario 64, Super Mario Sunshine, and various entries in the Mario Party franchise.
Despite being one of the most central species in the Mario series, very little solid information has been provided on the unique reproductive biology of the Yoshis.
The in-game Japanese text of Yoshi's Trophy in Super Smash Bros. Melee states that Yoshis reproduce asexually, meaning that they reproduce without a mate and are neither male nor female. This is supported by the Chef minigame in Game & Watch Galleries 2 and 4; after being fed long enough, the Yoshi produces an egg that eventually hatches into another Yoshi. The baby then takes its parent's place and proceeds to eat enough food to turn into an adult, eventually producing a fertile egg of its own, which then continues the cycle.
Other sources have also contradicted the asexual depiction of Yoshis. At least one of the Yoshis in Paper Mario refers to his "son", and in Paper Mario: The Thousand-Year Door, the Yoshi who sometimes appears on-board the Excess Express expresses his hatred of business trips due to them keeping him away from his "lovely wife". The original Mario Party also features a pair of Yoshis which appear to be one male and one female, although the exact nature of their relationship was not revealed. Additionally, while Japanese language rarely involves gender-specific pronouns, the character Yoshi is consistently referred to with masculine pronouns in translation, yet laying eggs is one of his trademarks. This apparent contradiction was addressed in Super Smash Bros. Brawl, where Snake assumes that Yoshi is a female because of his egg-laying abilities, only to be corrected by Otacon (both of whom use "it" rather than "he" or "she" when referencing Yoshi).
Though omnivorous, Yoshis eat mostly fruit, and in Yoshi's Story, they become happy when eating fruit of their own skin color. Melons are their favorite fruit regardless of skin color. Very few Yoshis, such as black and white Yoshis, can digest Peppers without hurting themselves. However, in Super Mario Galaxy 2, the playable green Yoshi can eat the Dash Pepper, turning him red-orange, and causing him to run very fast for a short amount of time. All Yoshis can eat enemies of various kinds, from large Koopas to plants. Also, if they eat a Bean Fruit, then they will lay a rare Neon Egg, the color of which depends on the Yoshi's own skin color.
Yoshis are capable of speaking human language, as proven by Yoshi in Super Mario World and Super Mario 64, as well as various other Yoshis in games like Yoshi's Story, Paper Mario, Paper Mario: The Thousand-Year Door, Super Mario Galaxy 2 (featuring the main Yoshi) and others. However, it has been suggested that Yoshis speaking human language is rare, as the main Yoshi must translate for Mario in Super Mario RPG: Legend of the Seven Stars and Mario Super Sluggers.
In older games (and in more recent ones, such as New Super Mario Bros. Wii), the voice of different Yoshis were a sound created by a backwards record scratching (in Super Mario World only the one green Yoshi spoke with a text bubble, though this was changed in the Super Mario Advance 2 version). In Yoshi's Story, the Yoshis are voiced by Nintendo musician Kazumi Totaka, who mutters the word "Yoshi" and unintelligible words (such as "gong" and "hup"); it is also worth noting that his voice was sped up to create the squeaky, childish voice of the Yoshis in this game.
Oddly, in the Mario & Luigi series, Yoshi still speaks with Super Mario RPG-style translation parentheses.
As a final note on language, the Super Mario Adventures comic joked that, much as would be repeated years later with Yoshi's Story, Yoshis could only speak the word "Yoshi" with various marks of punctuation.
Although the Baby Yoshis retain their squeaky voices in New Super Mario Bros. U and New Super Luigi U, their speech once again consists of "Yoshi" and it is translated for the player.
Mario Super Sluggers profiles
Team Player Yoshis