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 him punching the ground with his fists 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 either Mario, Luigi or Paper Mario, or they will receive massive damage and will be blown off the screen.

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 jump over the incoming Goombas, Spiny Shells and Bowser's fire breath. The player should also be careful of the Fly Guys, as they could damage Paper Mario if they make contact with the paper hero. 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 turns him arms into arm cannons and shoot crystal balls at the bros., and randomly shoot a fireball at them. 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 char status effect from the fireballs.

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.