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, much like Giant Bowser, wearing cardboard armor that resembles himself (apparently formed from Paper Bowser and his minions). During battle, some of the minions can break off and join the fight. While the cardboard armor still has it's head, 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.

Trivia

 * Shiny RoboBowser is the third final boss in the Mario & Luigi subseries to be a fusion of Bowser with another character (or in this case, multiple characters).
 * Shiny RoboBowser continues on with the tradition of the Mario & Luigi Series of the final boss being a different form of Bowser. Being the fifth in this pattern, joining Bowletta, Shrowser, Dark Bowser and Dreamy Bowser.