Shiny RoboBowser

Shiny RoboBowser is an enhanced version of Bowser and the final boss of Mario & Luigi: Paper Jam. After Mario, Luigi, and Paper Mario fight both the real-world Bowser and Paper Bowser for some time, Paper Bowser fuses with many of his paper minions, which Bowser then joins with to form the boss. Shiny RoboBowser is a giant version of the "real" Bowser, wearing cardboard armor in his own image (apparently formed from Paper Bowser and his minions). During battle, some of the minions can break off and join the fight. As Shiny RoboBowser takes damage, his armor breaks, ultimately destroying his helmet and allowing Bowser himself to be targeted; however, Bowser can regenerate his armor and heal damage by absorbing minions. While the cardboard armor still has its helmet, Paper Mario cannot use Trio Attacks, as Shiny RoboBowser will counterattack Paper Mario's hammer with his own and and trap Mario, Luigi, and Paper Mario in a similar setting to the Trio Attacks. After his HP is fully depleted, the boss explodes and Paper Bowser and Bowser fall to the ground, but Bowser falls off the arena and falls to his demise.

Attacks
One of Shiny RoboBowser's attacks involves clashing his fists a number of times, setting up mind games on the player, then punching the bros. After a few punches, he blows a stream of fire at them and then a giant fireball that slowly goes across the screen. The player must jump as soon as the boss punches, shoots a stream of fire and then the fireball towards Paper Mario, or they will receive massive damage and will be blown off the screen. The amount of times Shiny RoboBowser clashes his fists is the amount of times he will hit the bros before unleashing the stream of fire towards Paper Mario.

Shiny RoboBowser's next attack involves him leaping off-screen and then lands on the targeted bro, squishing them. The player must hammer him back to avoid massive damage. If the player doesn't hammer at the right time, Shiny RoboBowser will smash one of the bros, dealing massive damage and moderate damage to the rest of the party. Hammering him a few times will stop the attack.

Shiny RoboBowser can also turn him arms into paper wings and chase the bros. Paper Mario, as a paper airplane, should avoid the Fly Guys as Mario & Luigi jump over the incoming Goombas, Spiny Shells and Bowser's fire breath. If the Fly Guys hit Paper Mario, he will be out of the picture for a few seconds, leaving the bros. exposed to Shiny RoboBowser's fire breath. After a while, Bowser will home onto the player. Jump over him, hang on Paper Mario and land on his head to damage him.

Shiny RoboBowser also can turn him arms into arm cannons and shoot crystal balls at the bros., and shoot a fireball from his mouth at Paper Mario. Hammer back the fireballs and crystal balls at the boss to damage him, or the player will suffer major damage and randomly the dizzy status effect from the crystal balls or the burn status effect from the fireballs.

Shiny RoboBowser can also turn his arms into wheels, and chase the trio down. As they run, Mario, Luigi and Paper Mario must avoid Goombas and Fly Guys who will knock them back at the boss and eliminate them from the chase. Shiny RoboBowser will also shoot fireballs at them which will have the same effect as the minions. At the end of the road, a Chain Chomp will come towards the playable characters, and they must dodge it so it would crash on Shiny RoboBowser, knocking him over and ending the sequence in success. If any of the characters gets hit by the Chain Chomp, it will prevent it from crashing into Bowser, which will allow him to speed up and hit any remaining characters at the end.

At any given moment when the armor's helmet is active, or whenever Paper Mario uses his Trio Attack Hammer on the same condition, Shiny RoboBowser will unleash his own Paperizing giant hammer on the trio, trapping them in a paper version of the arena, and turning them into sheets of paper. During this sequence, Shiny Robo Bowser will shoot a stream of fire towards any of the three characters, and the targeted character must jump to avoid the fire. Jumping too early or jumping as a different character will attract the boss' attention, and release the fire on them after they jump, so it's advised for players to just jump as one character at a time. If any character still remains after the fire attacks, Shiny RoboBowser will get frustrated and unleashed a body slam on all remaining characters. Jumping at the right moment is the way to avoid damage.

All fire attacks deal critical damage to Paper Mario, and returning any fireball towards Shiny RoboBowser deals critical damage to his armor.

Trivia

 * Shiny RoboBowser is the third final boss in the Mario & Luigi series to be a fusion of Bowser with another character (or in this case, multiple characters). This also marks the first time Paper Bowser has been fused with another character.
 * Additionally, Shiny RoboBowser continues the series' trend of the final boss being a different form or derivative of Bowser, following Bowletta (Mario & Luigi: Superstar Saga), Shrowser (Mario & Luigi: Partners in Time), Dark Bowser (Mario & Luigi: Bowser's Inside Story), and Dreamy Bowser (Mario & Luigi: Dream Team).
 * Shiny RoboBowser is similar to the final boss of Yoshi's Safari, which was also Bowser wearing a suit of mechanized armor.