From the Super Mario Wiki, the Mario encyclopedia
Crinkle Goomba is a creased Paper Goomba who appears as an anti-hero in Mario & Luigi: Paper Jam. Like the other paper characters, he was released by a book containing the paper world. He appears throughout the game, often serving to give tutorials, sometimes to antagonize the trio.
Crinkle Goomba first appears when Mario, Luigi and Starlow enter Sunbeam Plains, along with another Paper Goomba. They confuse him with Paper Mario and Crinkle Goomba goes to get a closer look and is accidentally crumpled by the Bros., leaving him with a permanent crease. He and the other Goomba then battle the Bros. and after being defeated, Crinkle Goomba promises to return with "a whole stack".
Later, Crinkle Goomba once again attacks the Mario Bros. (who do not remember him), this time stacked with several other Paper Goombas. They fold into a large wheel and chase down the Bros., defeating both of them. However, Paper Mario arrives as the Goombas are leaving and defeats them. Crinkle Goomba complains about there being two Marios, but warns that they have not seen the last of him.
The trio find Crinkle Goomba in the Twinsy Tropics Dungeon, where he accidentally locked himself in a cell while on janitor duty (received as punishment for his failure). As a reward for helping him escape, he gives them a Battle Card set and tells them how to use the cards. He then sneaks out of the dungeon, claiming he doesn't want to work for Bowser anymore.
The trio meet Crinkle Goomba yet again on the way back to Twinsy Tropics. Despite his best efforts, they still do not remember him. He claims that he wants to help them reach Bowser's Castle and hitches a ride in Mario's pocket, much to Starlow's chagrin. When the group reaches the gate leading to Bowser's Castle, Crinkle Goomba betrays them and allows two Fire Bros to steal the medallion needed to get into the castle, revealing his plan to regain Bowser's favor. After reclaiming the medallion, the team finds him, but decide not to chase after him, as they do not want to waste any more time. Crinkle Goomba is not seen for the rest of the game.