From the Super Mario Wiki
“What's wrong with you dodos? You WANT to get hit with my boomerang?”
The Boomerang Bro (or Boomerang Brother) is a type of Koopa that, like Hammer Bros., specialize in the use of a certain item as a weapon. Instead of throwing Hammers like the Hammer Bros., Boomerang Bros. use Boomerangs that move back and forth to them. They are not as commonly found in the Mario series as their Hammer Brother relatives.
The physical appearance of Boomerang Bros. has changed throughout the series. Early artwork depicts them identically to Hammer Bros. of that era, with orange skin, along with black shells and helmets. The Boomerang Bros. in Paper Mario: The Thousand-Year Door and Super Paper Mario appear to be based on this colouration. In Super Mario Bros. 3 and its remakes, they have green skin and striped underbellies. Mario Superstar Baseball started the trend of depicting Boomerang Bros. with yellow skin and blue shells and helmets. Most games since have retained this depiction.
Super Mario series
Super Mario Bros. 3
Boomerang Bros. debut in Super Mario Bros. 3 as somewhat common enemies found primarily in Desert Land. They attack Mario or Luigi by throwing multiple boomerangs which circle back if they missed. In order to defeat a Boomerang Bro, Mario or Luigi need to jump on them or throw something at it, such as a Fireball or Shell. If one of the brothers can get close enough, the creature can also be defeated by Raccoon Mario's tail.
New Super Mario Bros.
In New Super Mario Bros., Boomerang Bros. appear as rare enemies, although they are one of the more common species of Hammer Bros. in the game. They appear only once in World 2-5, twice in World 7-3, and twice in World 8-7. Boomerang Bros. will, once again, attack Mario or Luigi by throwing boomerangs at them.
New Super Mario Bros. Wii
Boomerang Bros. also reappear in New Super Mario Bros. Wii, acting and appearing in much the same way as in the previous game. However, they are very rare, only appearing in World 2-1.
Super Mario Galaxy 2
Boomerang Bros. make their first 3D Mario appearance in Super Mario Galaxy 2. They first appear at Bowser Jr.'s Boom Bunker, and like the Hammer Bros., mostly appear in Bowser and Bowser Jr. galaxies. They also appear at the end of Grandmaster Galaxy, where they have to be destroyed to get the Power Star in the first mission and the second mission to get the Launch Star.
As usual, Boomerang Bros. use boomerangs to attack the player. Yoshi can catch the boomerangs with his tongue, and then spit them out as weapons against the Boomerang Bros. The player can flip them over by using Yoshi's tongue, by jumping on them or via spinning, and then walk into them to defeat them. It is possible to avoid boomerangs by crouching, and since Mario can walk while crouching, this makes it very easy to approach and defeat a Boomerang Bro.
Super Mario 3D Land
Boomerang Bros. reappear in Super Mario 3D Land and retain their behavior from Super Mario Galaxy 2. In some levels after World 4, Boomerang Bros. can drop Boomerang Flowers when defeated. They mostly appear in Bowser levels, but once Mario goes into the special worlds, he sees them around a multitude of places.
New Super Mario Bros. 2
The Boomerang Bros. return again in New Super Mario Bros. 2, operating in the same manner as before. Unlike the other Hammer Brother members that are in this game, the Boomerang Bro appears in five different levels, which are World 2-2, World 2-5, World Mushroom-Cannon, the second course of the Platform Panic Pack, and the first course of the Mystery Adventures Pack. In the latter, it is shown that they can be placed under the effects of a Gold Ring; when this happens, they toss three coins instead of their normal weapons, like the other Hammer Brother species.
New Super Mario Bros. U
Super Mario 3D World
Boomerang Bros. appear in Super Mario 3D World once again, in their usual blue helmet and blue shell combination. As with other games, they will throw boomerangs at the player and jump to another area after the boomerang returns to them. If the Boomerang Bro throws a boomerang and is defeated, the boomerang will still turn around and fly back towards the area from which it was thrown until it hits a wall.
As in Super Mario 3D Land, players can gain the abilities of Boomerang Bros. with the Boomerang Flower; the power-up can occasionally be collected after defeating a Boomerang Bro.
Super Mario Momotarō
In the short anime film Super Mario Momotarō, a Boomerang Bro becomes the second creature to join forces with Mario on his mission to rescue Princess Peach after helping it get up from being stuck on its back. During the battle with Bowser, the Boomerang Bro helps by hitting him on the head with its boomerang, as well as knocking out Iggy Koopa with it. After the battle, the Boomerang Bro helps Mario deliver the treasures Bowser stole back to their rightful owners.
The Super Mario Bros. Super Show!
The Adventures of Super Mario Bros. 3
Boomerang Bros. appeared several times in The Adventures of Super Mario Bros. 3, serving as soldiers in Bowser's army. Through the use of their boomerangs, these goons were practical in long range attacks. Unlike in the game, it was not uncommon for Boomerang Bros. to travel together in groups.
Nintendo Comics System
A Boomerang Brother made a relatively minor appearance in the Nintendo Comics System story The Kingdom Enquirer, where it attacks Mario and Toad with its boomerangs after the two heroes exit a Warp Pipe.
Nintendo Adventure Books
If Mario chooses to follow the main path to Fort Koopa in the Koopahari Desert in Double Trouble, he encounters the Boomerang Brothers (described as monstrous twins, despite the illustrated activity depicting four), who send a barrage of boomerangs at him after deciding the plumber looks tasty. Depending on how the accompanying puzzle is solved, Mario escapes either narrowly or easily and reaches Fort Koopa, or is hit in the back of the head by a returning boomerang while taunting them. This leads to one of the book's few Game Overs - one of them nonchalantly picks the knocked out Mario up by the leg, tosses him into a sack of old orange peels and other things he has picked up in his travels and, upon sheepishly agreeing with his brother that they're tired, plans to go home to make themselves "a nice pot of plumber soup."
In Yoshi's Safari, Boomerang Bros. occasionally appear as mini-bosses that attack Mario and Yoshi by throwing boomerangs at them. These Boomerang Bros. are difficult adversaries to defeat, as they possess a large amount of health and run back and forth quite quickly.
Unlike other experiences with Boomerang Bros., Mario can knock away an incoming boomerang by blasting them with his Super Scope.
Mario & Luigi series
A different kind of Boomerang Bro. appeared in Mario & Luigi: Superstar Saga. These Boomerang Bros., however, were rather tall and thin, wore sunglasses, and had sprouts growing from their heads.
Boomerang Bros. return as an enemy in Mario & Luigi: Dream Team. In the field, they chase Mario and Luigi very briefly when spotted, and then throw their boomerang at them. Like with the Beehoss' bees, touching the boomerang engages a battle with the owner of the touched boomerang.
In battle, Boomerang Bros. follow the orders of the Commander Lakitu in the background. A Boomerang Bro will approach the Bros., look at the Lakitus (in one instance) fly in a varying kind of circle and throw their boomerangs in a similar fashion to how the two Lakitus fly. Mario and Luigi must both at one point jump on (or over for the boomerang to hit the Boomerang Bro when coming back and damage it) the boomerang to avoid it. If the Commander Lakitus are defeated through use of a Taunt Ball, the Boomerang Bros.' own actions give away their attacks.
If there are two or more Boomerang Bros., the two Lakitu may raise a red M flag and green L flag, one raising one and the other raising the other. As they do this, the Lakitus move towards or away from the battle simultaneously. The Boomerang Bros. will throw their boomerangs in the air also simultaneously, for them to land on one bro each one after the other. Mario and Luigi must hammer these back to sender before they hit them. Whichever Bro's flag is being held by the Lakitus who's closer is the Bro who must smack their incoming boomerang away first. Additionally, the boomerang that will hit its target bro first also moves towards its target faster than the other, as indicated by the shadows on the ground. This takes up the attack turn of the Boomerang Bros. involved.
If they fly in a clockwise (when looking from the Bros.' point of view) circle, the boomerang will fly towards Luigi first. If anti-clockwise, it will fly towards Mario first. If the Commander Lakitus floats downwards and does two clockwise loops, the Boomerang Bro will jump then throw (this being another indicator of a jump throw), and the boomerang will fly towards Luigi first, however it flies the Bros. heads for the first loop, where they must idle, and then jump when it flies towards Luigi the second time. If it does this with anti-clockwise loops, it will fly towards Mario first, and he must jump first on the second loop.
Paper Mario series
Paper Mario: The Thousand Year Door
A single Boomerang Bro named Bamma appears in Paper Mario: The Thousand-Year Door as a competitor in the Glitz Pit alongside the Hammer Bro Hamma Jamma and the Fire Bro Flare. He sports a silver shell and helmet, and his boomerang bears a single red stripe.
Similar to the Boomerang Bros. in Super Mario Bros. 3, Bamma can attack Mario and his partners by either throwing a single boomerang or multiple ones by using either his Boomerang Throw or Multiboomerang moves, respectively.
Super Paper Mario
In Super Paper Mario, several Boomerang Bros. are brainwashed by Nastasia to serve under Count Bleck. The game also features a new, shadowed sub-species of Boomerang Bro known as a Dark Boomerang Bro.
Paper Mario: Sticker Star
“Boomerang! Bros.! Aw, two-for-one special on aisle three! Boomerang Bros. are outta their trees! Who cares if you swear a pair's unfair? We go together like pencils and pap-err!”
Boomerang Bros. have reappeared in the Nintendo 3DS game Paper Mario: Sticker Star. Unlike previous Paper Mario games, their helmets and shells are now the standard blue. Boomerang Bros. appear in numerous areas, starting from World 3. They are mostly found in outdoor areas. Outside of battle, they can attack Mario by tossing a Boomerang at him, which damages him. Their main attack is throwing a boomerang at Mario that causes damage twice, during the initial throw and when it returns. Their Boomerangs also sometimes spread a curse on Mario preventing some of his attacks to be successful as well as keeping him from using evasive stickers. Since their defense is 2, Boomerang Bros. are immune to Hopslipper stickers. Sometimes after battle, a Boomerang Bro may drop a Boomerang sticker. A couple of Boomerang Bros. stop and ambush Mario to prevent him from getting the Comet Piece. These same Boomerang Bros. (after defeating Gooper Blooper) guard a Heart Block and a HP Plus however instead of fighting together, they are fought individually. The 2 Boomerang Bros this time are assisted by 2 Ninjis (One in each battle) and one Snifit.
Mario Baseball series
Mario Superstar Baseball
In Mario Superstar Baseball, one of the alternate color schemes for the game's playable Hammer Bro is a Boomerang Bro that wields a large boomerang in place of a baseball bat in the same way that Hammer Bro wields a hammer instead of a bat.
Boomerang Bro is a power-type player in the game, and can easily obtain home runs. Beginning with this game and beyond (excluding Super Paper Mario), Boomerang Brothers wear a blue helmet and a blue shell, similar to blue-shelled Koopa Troopas.
Mario Super Sluggers
Boomerang Bro is also a playable character in Mario Super Sluggers. However, unlike in Mario Superstar Baseball, he has average pitching and fielding abilities, and his batting is tied with the Hammer Bro, while inferior to the Fire Bro.
Mario Golf: World Tour
In Mario Golf: World Tour, one of the names that can appear on the tournament scoreboard is "Boomerang Bro".
Mario Kart 8Sunshine Airport, there are several aircraft that represent Boomerang Bros International Airlines.
Paper Mario series stats and tattle information
Names in other languages