From the Super Mario Wiki
“LAAAAADIES AAAAAAND GENTLEBUDDIES!”
Snifits are similar to Shy Guys with gasmasks, and an extended nozzle for a mouth. The extended nozzle can fire bullets, projectiles, or other objects. Though Snifits first originated in Yume Kōjō: Doki Doki Panic, they have since become somewhat frequent enemies in the Mario series. Snifits usually wear red robes, but they have also worn gray, green, blue, black, and pink.
 Super Mario Bros. 2
In Super Mario Bros. 2, Snifits (shown here to be affiliated with the mysterious 8 bits) are less common than their cousins the Shy Guys, and come in four colors: red, gray, green, and pink. Only in World 2 and World 6 were Snifits gray and green. There was only one red Snifit in the entire game (found in World 3-3). This trait was later changed, as most Snifits now are red.
There were only a few changes between the different colors. Green and gray Snifits stood in place jumping and fired, pink Snifits acted like pink Shy Guys (turning around on edges), the red Snifit moved about like red Shy Guys (falling down ledges), and it was smarter, as it could change direction towards the player. In the Super Mario All-Stars version of Super Mario Bros. 2, the pink Snifits are blue and green and gray ones are now both gray.
It is mentioned in the Super Mario Bros. 2 manual that the projectiles Snifits fire are made from a form of nightmare and are actually produced from the Snifit itself.
 The Super Mario Bros. Super Show!
Snifits made several appearances in The Super Mario Bros. Super Show!, where they were most often portrayed as the minions of King Koopa and as shock troops of the Koopa Pack. In some of their appearances in The Super Mario Bros. Super Show!, such as in "The Unzappables", Snifits were used in a manner similar to handheld machine guns. In the episode "On Her Majesty's Sewer Service", a Snifit shot Bullet Bill-like projectiles towards the Mario brothers. They mentioned, "Good thing this window is Snifit-proof...".
 Nintendo Comics System
Snifits were also featured in several issues of Nintendo Comics System, where they appeared to be high-ranking minions of Bowser, as they are shown to command and train his Shy Guy troops. One particular, unnamed Snifit was featured prominently in the Nintendo Comics System issue "Duh Stoopid Bomb!", where the Snifit, after accidentally becoming super-intelligent after being caught in the explosion of a Smart Bomb, usurps Bowser of his armies.
 Super Mario Adventures
 Super Mario Bros. film
Snifits also appeared in the Super Mario Bros. film, where they are shown to be the garbagemen of Dinohatten, instead of soldiers in King Koopa's army, cleaning sludge with the use of a vehicle referred to as a Sludge Gulper. Several were ambushed by the Mario Bros. when trying to get back to Dinohatten alongside Iggy and Spike. Although in shape, they resemble humans, their vocal sounds imply that they aren't completely human, as they possessed vocal sounds similar to that of chipmunks.
 Super Mario RPG: Legend of the Seven Stars
In Super Mario RPG: Legend of the Seven Stars, blue Snifits appear as enemies in Booster Pass and Booster Tower. They were renamed Spookums in the English version of the game, however, their Japanese name is the same. Some of these blue Snifits, known as Apprentices, train on an obstacle course at Booster Pass. Snifits, instead of shooting their traditional bullets, shot Bullet Bills.
Three normal Snifits, aptly named Snifit #1, Snifit #2 and Snifit #3 appear as the minions and playpals of Booster. Snifits #1, #2 and #3 first meet Mario after he defeats Punchinello in Moleville, where they are hunting beetles for Booster. While hunting these beetles, Snifits #1, #2 and #3 accidentally reveal to Mario that "a princess who fell from the sky" is being imprisoned in Booster Tower.
Later, in Booster Tower, Mario, Geno, Mallow and Bowser can battle Snifits #1, #2 and #3, all of whom, attack by shooting Bullet Bills. After entering Booster's playroom, Mario would need to try and hide from Snifits #1, #2 and #3 behind curtains as the trio of Snifits search for Booster's lost Mario Doll. If Mario was found behind these curtains too many times by Snifits #1, #2 and #3, he would be forced to battle Snifits #1, #2 and #3 and their master, Booster. If he remained hidden, Booster joined in and found his Mario Doll, but it's too high for him to get so Mario knocks it down and Booster rewards him with a Amulet.
On Booster Hill, Snifits #1, #2 and #3 would try to ram Mario as he raced up the slope after Booster and Princess Toadstool. Mario could jump on the heads of Snifits #1, #2 and #3 to get a boost up Booster Hill.
Finally, in Marrymore, after Booster barged into the Marrymore Chapel (interrupting the wedding of Raz and Raini) Snifits #1, #2 and #3 acted as guards, making sure no one interrupted Booster's forced wedding to Princess Toadstool. After breaking into Marrymore Chapel, Snifits #1, #2 and #3, after learning that Princess Toadstool had lost her accessories, began to search for them and relied on Mario to bring the accessories they had found to Princess Toadstool.
During the battle against Raspberry, Snifits #1, #2 and #3 and Booster would appear; it was Snifits #1, #2 and #3 who inadvertently destroyed Raspberry for Mario, after the trio convinced Booster to devour the living confectionery.
A Snifit can later be seen in Seaside Town, acting as the manager of Beetles Are Us. Several dozen Snifits also make a small cameo in the ending cinematic of Super Mario RPG: Legend of the Seven Stars, with the entire audience of Booster's wedding to Valentina being composed of them.
 Mario Party series
 Mario Party 3
Snifits appear in several installments of the Mario Party series, such as in Mario Party 3, where one appears as the starting partner of Princess Daisy in the game's Duel Mode. It has an attack power of 2, a stamina stat of 2, and a salary of 5 coins per turn. It sometimes finds 2-4 coins during a turn.
 Mario Party Advance
In Mario Party Advance a Snifit is found in Horror Condo. It lives on the second floor of the condo. However, it isn't happy with the condo, as it isn't actually haunted. The player has to convince the Boos to come to the condo and haunt it. Upon returning to the condo, Snifit rewards the player with the Gaddget Porta-Gust. The ending states that he still lives at the condo, but he is getting tired of the Boo sightings.
 Mario Kart series
Snifits have always been rare sights in Mario Kart games, and they did not debut in the series until Mario Kart: Super Circuit. In that game, they only made a minor cameo appearance in the Sunset Wilds course, where they could be viewed alongside other semi-obscure enemies on totem pole obstacles - the other enemies being Shy Guys and Toadys. Their next appearance in the series was Mario Kart: Double Dash!!, where they made another small cameo as characters in the audience of Waluigi Stadium. Mario Kart Wii is their most recent appearance, still in the audience of the returning Waluigi Stadium.
 Mario & Luigi series
 Mario & Luigi: Superstar Saga
Standard Snifits have technically not appeared in the Mario & Luigi series, but it appears to be traditional for debuting Snifit subspecies to appear. For instance, during their Mario & Luigi: Superstar Saga adventure, Mario and Luigi met up with the laser-emitting Laser Snifits (actually Woohoo Hooniversity's transformed Beanish professors), the cactus-like, spike-shooting Spiky Snifits, and the ice-shooting Ice Snifits.
 Mario & Luigi: Partners in Time
In contrast to this handful of sub-species in the prequel, Mario & Luigi: Partners in Time saw only one Snifit subspecies, the Snifaros, which are notable for fighting alongside completely normal (though never named) Snifits.
 Mario & Luigi: Bowser's Inside Story
In Mario & Luigi: Bowser's Inside Story, the only time a Snifit appears is during enemy battles with a sub-species of flower-like Snifits called Flifits. When Flifits lose their petals, a Snifit wearing butterfly wings will appear to pour some water on them and heal them.
 Yoshi series
 Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
As Super Mario World 2: Yoshi's Island is set in the past, this game marks the Snifits' first chronological appearance.
Snifits were uncommon enemies found in some of the game's various castle levels, where they would attack Yoshi and Baby Mario by shooting projectiles at them. The projectiles in this game were oval, instead of circular, and would go through walls. In this game, Snifits could always walk around and sometimes changed directions towards Yoshi. There was only one color of Snifit in this game: pink. Yoshi could defeat a Snifit in Super Mario World 2: Yoshi's Island by jumping on it, swallowing it with his tongue, or by simply shooting it with an egg.
 Yoshi Touch & Go
Although true Snifits never appear in Yoshi Touch & Go, being replaced by Fly Snifits, what appear to be normal Snifits appear on the game's high scores screen. They have sprites similar to those of Fly Snifits.
 Yoshi's Island DS
 Mario vs. Donkey Kong series
A small toy version of Snifits called Mini Snifits first appeared in Mario vs. Donkey Kong 2: March of the Minis, being only found in the level Jungle Hijinks. They fire five bullets at a time. Mini Snifits later re-appeared in Mario vs. Donkey Kong: Mini-Land Mayhem!.
 Paper Mario: Sticker Star
Snifits make their Paper Mario debut in the Nintendo 3DS game Paper Mario: Sticker Star. Snifits are first present in World 3, where they are the most common enemy found. Snifits can be encountered on land or in poisonous water, which they are implied to enjoy. In battle, the Snifit can either spit out one bullet or a barrage of three. If Mario uses a Tail sticker, the Snifits will attempt to push. If successful, Mario will lose the Tail sticker. If Mario is able to attack multiple times via Battle Spinner, a Snifit may also knock away one of Mario's attacks. Snifits may also appear in Bowser's Snow Fort alongside Shy Guys. They can be found in the trash area of Shy Guy Jungle before the player uses the goat or vacuum things. Mario may pull one out and battle it.
A game show called Snifit or Whiffit (Hit It or Snifit in PAL versions) is hosted by a Snifit who goes by said name. Mario must participate in this game in order to obtain a Wiggler Segment, which is necessary for progress. If Mario completes the three challenges, Snifit asks him to participate in another one, which combines the first two challenges. If Mario wins this final challenge, he is awarded with the Radiator Thing (Coins if he returns and has already collected the Radiator).
 Notable Snifits
 Names in other languages