Koopa Bros.

The Koopa Bros. are a group of characters who appear in Paper Mario. They guard the first star spirit in Chapter 1.

Plot
The Koopa Bros. are a group of four Koopas consisting of Red, Yellow, Black, and Green. They were first seen introducing themselves to Bowser as the guardians of the first Star Spirit (however, Bowser pointed out that no one was currently watching it if they were there). They disguise themselves as a gang of Toads that are blocking the path to Koopa Village. Merlon manages to reveal their true form, and they run off, frightened, back to their fortress. When Mario attempts to take the path to their fortress, they find the bridge is out of order (hinted by the sign the Koopa Bros. left) Eventually, Mario gets Kooper as a party member and manages to cross the bridge and enter their fortress. There are plenty of traps and switches throughout the dungeon and Mario manages to meet up with the Koopa Bros. at the top, who set off Bullet Bill cannons. Once those are defeated, "Bowser" appears and fights Mario, but it's obvious the Koopa Bros. are inside the suit. Once damaged enough, the Bowser suit explodes to reveal the Koopa Bros. and they start the battle.

Strategy
The Koopa Bros. can be knocked on their back after two successful hits (one from Mario's hammer, and another from Bombette's dash move). They remain on their back for two turns. Their special move consists of them stacking together and spinning straight into Mario. (the amount of damage they do is equal to the amount of Koopas in the stack). All four Koopas have to be defeated, Red having the most HP.

Aftermath
After Mario defeats the Koopa Bros, they get tossed into the jail cell (the same one that housed Bombette) and supposedly stay trapped there for the remainder of the game.

Towards the end of the game, after reaching the second trivia door in Bowser's Castle, the Koopa Bros. make an appearance, ready to fight Mario. Their fight is interrupted by an extremely angry Jr. Troopa, who manages to knock the Koopa Bros. out, much to the trivia door's surprise.

The Koopa Bros. appear in the ending credits on their float, which is soon destroyed by a couple of bob-ombs.