Roger the Potted Ghost
From the Super Mario Wiki
Roger the Potted Ghost (initially just the Potted Ghost) is a boss character from Super Mario World 2: Yoshi's Island and is located in the final castle of World 2. Roger started out as a lifeless flower pot, but was transformed by Kamek's magic into a large ghost named Roger. He's amorphous, but his face resembles Dangling Ghosts and Caged Ghosts.
To defeat him, the Blue Yoshi has to push Roger and his pot over the edge of the platform. This is a difficult process, as two green Shy Guys are pushing Roger in the opposite direction. Throughout the battle, Roger will lunge at the Blue Yoshi, knocking him or her away. He also shoots blue flames which home in, forcing the blue dinosaur to stop pushing and get out of the way. If the Shy Guys are pushed off the edge before Roger himself, he will be helpless and won't be able to move.
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