Super Paper Mario/Chapter 8: Castle Bleck

Chapter 8-1: The Impending Darkness
Boss: O'Chunks-Bowser is the only character who plays agaisnt this boss. He will vanish afterward, and won't appear until your fight with Count Bleck at the end of the chapter. This will happen to other characters though the rest of the chapter.

Chapter 8-2: The Crash
Boss:Mimi-Peach is the only character you can use agaisnt this boss. Afterward, Peach vanishes and appears again at the start of the battle with Count Bleck.

Chapter 8-3: Countdown to Destruction
Boss:Dimentio-Luigi is the only character you can use to fight Dimento, and leaves the group after the battle and returns at the start of the fight with Count Bleck.

Chapter 8-4: Tippi and Count Bleck
Boss1:Count Bleck HP:150  Attack:8

Boss2:Super Dimentio HP:200  Attack:6

Note: After Tippi leaves the group at the end of the game, you can buy Tipton (an almost exact copy of Tippi) for 999 coins from Francis, the boss of chapter 3.