From the Super Mario Wiki
Buzzy Beetles (or simply Buzzies) are turtle-like creatures with hard, outer shells that are often blue. Buzzy Beetles will hide in their shells if jumped on, and, like a Koopa Shell, can be kicked to eliminate more enemies. The shell of the Buzzy Beetle is strong enough to resist fireballs, and as such, they cannot be defeated by fire. In a way, they are the polar opposite of the Spinies; enemies who are immune to jumps, but vulnerable to fireballs. When a "bah" is heard in the music, they will do a short jump just like Goombas.
Super Mario series
Super Mario Bros.
Buzzy Beetles first appear in World 4-2, an underground level of Super Mario Bros.. Like a Koopa Troopa, they will hide in their shell when jumped on, and can be kicked around the level. However, Mario and Luigi cannot defeat them with fireballs. After the player completes the game and restarts, all Goombas will be replaced with Buzzy Beetles.
In World 3-4, a Buzzy Beetle is one of the seven Bowser Impostors. Unlike all other Buzzy Beetles, this one is affected by fireballs; like all the other False Bowsers, five fireballs will destroy him.
In a playthrough, Buzzy Beetles take the place of all the Goombas after the game has been cleared once.
Super Mario Bros. The Lost Levels
In Super Mario Bros. The Lost Levels, Buzzy Beetles return just as they did in the previous game. They are also found underwater occasionally in World 9, along with all the other enemies. When underwater, Buzzy Beetles are completely invulnerable, since no enemies can be jumped on while underwater.
Super Mario Bros. 3
In Super Mario Bros. 3, Buzzy Beetles return, acting the same way as they did before. Here, Buzzy Beetles can also climb and walk on the ceiling. To attack intruders, they can drop, and spin along the ground to attack. In the Game Boy Advance remake Super Mario Advance 4: Super Mario Bros. 3, when the Red Switch e-Reader Card is scanned, all walking Koopa Troopas are replaced with Buzzy Beetles. In addition, there is a flying variation called Para-Beetle, which are found only in one level.
Super Mario World
Buzzy Beetles also appear in Super Mario World. They are still resistant to fireballs; however, Yoshi can swallow them whole, unlike Koopa Troopas' shells, which Yoshi cannot immediately swallow. They hide in their shells when jumped on, as opposed to sliding out, as the Koopas sometimes do when stomped. Spike Tops, Buzzy Beetles with a spike on their back, which cannot be jumped upon, are introduced in this game. Yoshi or a successful Spin Jump will protect Mario and Luigi from getting hit by the spikes. This game also introduces Bony Beetles, which are undead skeletons of a Buzzy Beetle.
New Super Mario Bros.
Buzzy Beetles reappear as enemies in New Super Mario Bros., although they are very rare in this game. In fact, they only appear in two levels, World 5-C, and World 6-Tower 2, where during the start of the level, the beetle is flipped over. They behave similar to their appearance back in Super Mario Bros. 3. As in Super Mario Bros., they can be kicked when stomped on, and are impervious to fire. Spike Tops reappear in this game also.
New Super Mario Bros. Wii
Buzzy Beetles later reappear in the sequel, New Super Mario Bros. Wii. In World 6-3, a big group of Buzzy Beetles can be seen on the ceiling, and will fall on Mario and the group, as they did in Super Mario Bros. 3. In both games, Buzzy Beetles hop to the electronic vocal "bah" in the background music. They also appear in 8-1, and these ones don't walk off ledges, unlike normal Buzzy Beetles, mainly because they walk off ledges that lead to a body of lava. Kamek may also transform blocks into them during his boss fight in the World 8-Tower. Spike Tops also reappear again. However, the most notable appearance is the reappearance of Para-Beetles who have not been seen since The Adventures of Super Mario Bros. 3, and a new sub-species called Heavy Para-Beetle. They only appear in World 7-6.
Unlike in Super Mario World, Yoshi can't completely eat Buzzy Beetles. However, he can spit out their shells in the same manner as with a Koopa Troopa shell.
Giant Buzzy Beetles were originally going to appear in this game too, but they never appeared in any levels in the final game. However, through hacking methods, it is possible to use one in a level.
New Super Mario Bros. 2
New Super Mario Bros. U
Buzzy Beetles also appear in the Nintendo Wii U title, New Super Mario Bros. U. Bony Beetles also make a return since their debut in Super Mario World, now resembling an undead Buzzy Beetle. The large variety of Buzzy Beetle, which first appeared in Paper Mario: Sticker Star, also appears.
Super Mario Bros.: Peach-hime Kyushutsu Dai Sakusen
In Super Mario Bros.: Peach-hime Kyushutsu Dai Sakusen, two Buzzy Beetles (although gold in color) made a brief appearance in the movie where they attempted to attack the heroes but were defeated by Mario when he used a Fire Flower to shoot them with a fireball, despite the fact that Buzzy Beetles are ordinarily immune to fire attacks in the games.
Nintendo Adventure Books
Buzzy Beetles appear as enemies in Hotel Mario. They are introduced in Larry's Chillton Hotel, and have a redesigned appearance, fit for the chilly environment. Unlike in other appearances, they behave more like Goombas except they will walk in Mario's direction when he arrives on their floor.
Paper Mario series
Buzzy Beetles also appear in the Paper Mario series. They are shell enemies like the Koopa Troopas, meaning they can be flipped over when they are jumped on or by a POW Block. However, unlike the Koopas, Buzzy Beetles do not spend a turn struggling on their back; they can right themselves on their very next turn, though they can't attack on that turn. Fire attacks won't hurt them at all. However, if they are flipped on their back, they lose the fire immunity. Related enemies are Spike Tops, Parabuzzies (which now lose their wings when they are stomped), and Bony Beetles. One of the new types of Buzzy Beetles are Spiky Parabuzzies, which flies and have a spike on their back, making it hard to damage them. In Paper Mario, Paper Mario: The Thousand Year Door, and Super Paper Mario, Buzzy Beetles eyes and entire face are visible, unlike the other games, where most of its face is covered revealing glowing eyes.
In Paper Mario, Buzzy Beetles appear in the Toad Town tunnels and in the Dry Dry Ruins. In Dry Dry Ruins, several Buzzy Beetles climb on the ceiling, like in Super Mario Bros. 3. They can drop on Mario to attack them, and he cannot jump on them while they are hanging from the ceiling. However, he can use a badge to cause an earthquake, which causes the Buzzy Beetles to fall to the ground. Spike Tops, which are red in the game, are enemies fought inside Mt. Lavalava; and Bony Beetles are found in Bowser's Castle.
Buzzy Beetles also appear in Toad Town Tunnels.
Paper Mario: The Thousand-Year Door
In Paper Mario: The Thousand-Year Door, the first Buzzy Beetles in the game are fought in the Glitz Pit. They are red Spike Tops; however, as regular Spike Tops in the game are blue, they are called Red Spike Tops in the game. Two of them build up the fighting team known as the Tiny Spinies.
Regular Buzzy Beetles later appear as enemies in the cave under the well of the Creepy Steeple, as well as the Pirate's Grotto and the Pit of 100 Trials. Regular Spike Tops and Spiky Parabuzzies are also found in Riverside Station.
The game also features Sky-Blue Spinies. It is implied that these are a cross between Buzzy Beetles and Spinies, as they are called "Käfer-Stachis" ("Buzzy Beetle Spinies") in the German version of Paper Mario: The Thousand-Year Door.
Super Paper Mario
Buzzy Beetles reappear in Super Paper Mario. The game introduces a new sub-species, the Stone Buzzies: Buzzy Beetles with stone shells that always take three hits to be defeated. They are found in the Downtown of Crag. The game also features "dark" versions of several Buzzy Beetles, notably Dark Spike Tops and Dark Stone Buzzies, found in the Flopside Pit of 100 Trials.
Paper Mario: Sticker Star
Buzzy Beetles appear in Paper Mario: Sticker Star where they are inside cave places and in 2D underground segments. Their appearance is similar to that of their New Super Mario Bros. counterparts. The Buzzy Beetle's only attack in this game is going into its shell and ramming into Mario. A Buzzy Beetle's shell toss attack sometimes gets Mario Dizzy. If Mario jumps on it but does not defeat it, it will hide inside its shell for a short time. When hiding, no attack will damage it. Mario can jump on it again to kick it at enemies behind it, damaging them. Spike Tops and Bony Beetles also appear in this game, as well as the introduction of Shiny Buzzy Beetles. A Buzzy Beetle may rarely drop a Flashy Shell sticker. Buzzy Beetles are aided by nobody except Goombas.
If a Buzzy Beetle is upside down, it will try to get back up, unlike the Koopa Troopas these Buzzy Beetles will always get back up as soon as they are flipped over, and rarely make the First Strike however 5 five Buzzy Beetles in Drybake Stadium are smart guards and will do their best to prevent Mario from leaving the rooms. They are also the last Buzzy Beetle fight and the only fight to have a group of 5.
An optional mini-boss, Big Buzzy Beetle also appears in the game.
Mario Party series
Mario Party 6
Buzzy Beetles make a cameo appearance in the 2-vs-2 mini-game, Slot Trot. They appear as one of the images on the slots. They appearance here is similar to the Paper Mario series appearance, except for their claws and paws, which aren't white.
Mario Party DS
Buzzy Beetles makes a cameo appearance in the Memory Mash minigame as pictures of a possible match. These Buzzy Beetles get their appearance from the Paper Mario series. These pictures are identical to Mario Party 6 Slot Trot ones.
Mario Party 8
Buzzy Beetles appear solely in the Battle Minigame, Glacial Meltdown in Mario Party 8. A Lakitu throws them onto the ice making them both obstacles and weapons for the players to use to knock the opponets off the ice. It is unknown why the Lakitu threw Buzzy Beetles instead of its species' normal Spiny accomplices.
Mario Party 9
Some Buzzy Beetles appear in the minigame Goomba Spotting, as a trick in order to lead the player into miscounting, since only the number of Goombas is counted at the end of the minigame. A Buzzy Beetle is also on one of the puzzles in Jigsaw Jumble.
Mario Party: Island Tour
Puzzle & Dragons: Super Mario Bros. Edition
Buzzy Beetles appear as enemies and potential allies in Puzzle & Dragons: Super Mario Bros. Edition. They have the dark attribute, and their skill involves reducing enemy damage for three turns. Enemy Buzzy Beetles also have a skill which can prevent any character who has the light attribute from attacking for two turns.
Super Mario Maker
Official profiles and statistics
Paper Mario series
Trophy Information from Super Smash Bros. Brawl
Names in other languages