In Super Smash Bros. Ultimate, Rayman appears as a Spirit collectible.
Spirits are collectible representations of characters, creatures, objects, and other concepts from video-game series. Players can obtain them through Spirit Battles, the Spirit Board, shops, adventures, and other in-game activities. Once collected, a Spirit can be equipped to a playable fighter to modify abilities or provide helpful effects.
Rayman is represented by a primary Spirit associated with the Rayman series. His appearance does not make him a playable fighter in Ultimate; that is the key distinction behind this question. Spirits may appear in battle as themed opponents or provide equipment effects, but they are separate from the game's fighter roster.
A common mix-up is to call Rayman a trophy because earlier Super Smash Bros. games prominently featured collectible trophies. Ultimate replaced the traditional trophy-collection focus with Spirits, so “Spirit” is the precise answer here.