Koopa Bros.

"HI-YAAA! Here come the Koopa Bros!! Uh-huh! Oh yeah! We're the coolest of cool!"

- Koopa Bros.

The Koopa Bros. are a quartet of costumed ninja Koopa Troopas; they are followers of Bowser and his Koopa Troop. The Koopa Bros. consist of Green Ninjakoopa, Yellow Ninjakoopa, Black Ninjakoopa and the leader, Red Ninjakoopa. They are all egotistical and obsessed with being cool, though they have a great deal of respect for Bowser and each other.

It is mentioned by several characters throughout Paper Mario that the Koopa Bros. were originally inhabitants of Koopa Village, apparently living in it around the same time as Kent C. Koopa. Eventually, the Koopa Bros. grew tired of Koopa Village, finding its serene environment and lack of excitement boring. The Koopa Bros. eventually left Koopa Village and traveled to Koopa Bros. Fortress (which was apparently then in ruin), whose Bob-ombs they seemingly befriended.

The Koopa Bros. eventually became conceited and corrupted due to the influence of Bowser and Kammy Koopa, who had taken a liking to them. Enslaving the Bob-ombs inhabiting Koopa Bros. Fortress (which they seemingly then rebuilt), the Koopa Bros. worked them non-stop, and if they rebelled, they would be imprisoned. When Bowser stole the wish-granting Star Rod and imprisoned the Star Spirits, the Koopa King entrusted the elder Star Spirit, Eldstar, to the Koopa Bros.

Super Mario-Kun
Prior to their appearance in Paper Mario, the Koopa Bros. appeared in Super Mario-Kun, a Japan-exclusive manga. In their first appearance in Super Mario-Kun, the Koopa Bros. appeared to attack Mario, Luigi, and Yoshi in a platform-filled area, taking on various disguises and utilizing shell-like shurikens in combat. The Koopa Bros. later appeared in the Paper Mario adaptation of Super Mario-Kun.

Paper Mario
The Koopa Bros. first appeared in Paper Mario in Princess Peach's Castle, where they appeared to reassure both Kammy Koopa and Bowser that they could stop Mario, and also showed them a technique, which impressed Bowser; the Koopa Bros. were later sent running from Princess Peach's Castle after informing Bowser that they hadn't actually posted someone to guard the captured Eldstar, a show of incompetence and lack of thought which infuriated Bowser.

At first, the Koopa Bros. simply attempted to stop Mario from reaching Pleasant Path and their fortress by disguising themselves as dark colored Toads and by blocking the path to those locations, saying that dangers lurked there. With help from Merlon, who saw through the Koopa Bros.' disguise, Mario was able to cause the Koopa Bros. to retreat. The Koopa Bros. attempted to impede Mario's progress in Pleasant Path as well, creating various obstacles and having various minions patrol the area.

When Black Ninjakoopa found that Mario and his allies had reached Koopa Bros. Fortress, he alerted his brothers and they proceeded to set about making various traps and obstacles in their home, all of which Mario passed. In a last-ditch effort to stop Mario, Red Ninjakoopa had his brothers set up three Bill Blasters on top of the fortress, which Mario managed to pass. Reaching the Koopa Bros. at last, Mario, before he could battle the Koopa Bros., had to battle their creation, a poorly constructed facsimile of Bowser. When their fake Bowser was destroyed, the Koopa Bros. would attack Mario using a whirling tower attack. Regardless, Mario still defeated the Koopa Bros., who were sent tumbling into the prison of their own fortress, incapable of escaping.

At Mario's House, a letter from the Koopa Bros. meant for Mario can be found; the letter is filled with threats uttered by the Koopa Bros. at Mario, with the Koopa Bros. swearing revenge on him. Also, for a short while after their defeat, the Koopa Bros. can be found in the prison of their fortress. Later, the Koopa Bros. evidently managed to escape this prison, as, if Mario visits it later, the Koopa Bros. will be gone.

The Koopa Bros. later appeared at Bowser's Castle under the employ of the castle's third living door; the Koopa Bros., who claimed to have become stronger (even renaming themselves "the Super Ultra Mighty Koopa Bros. the Great") prepared to fight Mario when Jr. Troopa appeared and simply knocked them aside easily.

During the ending parade of Paper Mario, the Koopa Bros. appear riding a float constructed out of the remains of their old Bowser construct. As the Koopa Bros. strike a pose, several Bob-ombs appear and explode near them, covering them in soot.

Red Ninjakoopa
The leader of the Koopa Bros., Red Ninjakoopa has authority over his siblings and seems to come up with their plans. When Mario reaches the roof of the Koopa Bros. Fortress, Red Ninjakoopa has the other three Koopa Bros. open fire on him with a barrage of Bullet Bills.

Black Ninjakoopa
Black Ninjakoopa is the possible second-in-command of the Koopa Bros. and the one seen apart from his brothers most often. When Mario reaches Koopa Bros. Fortress, it's Black Ninjakoopa who reports this to Red Ninjakoopa and his other brothers, who increase their bases's security accordingly. Additionally, when Mario first enters the chamber where he battles the Koopa Bros., its Black Ninjakoopa who appears to greet him, before leaving with Red Ninjakoopa to pilot the Bowser???

Notably, Black Ninjakoopa is miscolored blue in the official artwork. This was likely a mistake on the artist's part.

Green Ninjakoopa
Upon being alerted to Mario's arrival at the Koopa Bros. Fortress by Mario, Green Ninjakoopa took defence precautions and had a key sealed away and guarded. When Mario found Green Ninjakoopa while he was doing this, the Koopa Bro. taunted Mario and fled.

It is interesting to note that Green Ninjakoopa is one of the few battle-friendly Green Koopa Troopas in all of the Paper Mario series, save for the Green Koopa Troopas of Super Paper Mario (which even allowed completely normal green Koopa Troopas to be fought in its The Bitlands area). He is apparently the third-in-command of the Koopa Bros.

Yellow Ninjakoopa
When Mario gets deeper into the Koopa Bros. Fortress, Yellow Ninjakoopa sets a trap for him; when Mario hits a rigged ? Block, a trapdoor opens beneath him and sends him falling into the Koopa Bros.' dungeon; as Mario falls, Yellow Ninjakoopa taunts and jeers at him.

Ironically, Yellow Ninjakoopa's plan of trapping Mario in the dungeon backfired, as Mario met Bombette in the dungeon and also managed to break several other Bob-ombs out of it. He also appeares to be the last-in-command of the Koopa Bros.

Trivia

 * The Koopa Bros. are obvious spoofs of the Teenage Mutant Ninja Turtles, being turtles, ninjas wearing similar colored costumes and having a similar group name.
 * The song that plays when the Koopa Bros. are fought is a remix of the Hammer Brothers battle theme from Super Mario Bros. 3.
 * The music that plays when the player first enters the Koopa Bros'. chamber is the music that plays in Donkey Kong when Donkey Kong climbs up the ladders in the intro.
 * The song that plays when the Koopa Bros. fired Bullet Bills at Mario and company is a remix of the Koopalings' Airship theme from Super Mario Bros. 3.
 * After defeating the Koopa Brothers, much later in the game, Mario will be asked a question by Chuck Quizmo about which Koopa Brother doesn't exist. The right answer was Blue Ninjakoopa, and the other two options were Black Ninjakoopa and Red Ninjakoopa.
 * The Koopa Brothers are the only chapter bosses (aside from Bowser) that were seen again, prior to the ending parade. They are also the only bosses to send Mario a letter.
 * It is implied that Kent C. Koopa taught them everything they know about fighting.