Sakurai teases, but he's never truly misleading. Also, I dunno about anyone else, but I've been following Nintendo's revealing of information about various topics for at least two decades. They have a certain style to them that is hard to describe, and revealing Rayman like this as a playable character is just not something they tend to do.
I do agree this trophy is weird, but if you think about it, there's a lot better you could say. Rayman Legends was a pretty significant early "exclusive" for the Wii U, and while I doubt Nintendo is super happy with how Ubisoft handled it, Ubisoft has nevertheless still probably done more for the Wii U than most other major publishers (Child of Light also had a Wii U release). Ubisoft likely wanted the free advertising for their game in smash, and it's just good business from Nintendo to give them a nod like this. Something like a playable character would require some serious business dealings neither company may want, but it's not exactly legally difficult for one company to gift another a small bit of advertising. Heck, that PotD post may have been a bigger part of the deal than the trophy being in the final game itself; for 24 hours on the smash 4 site which gets a ton of hits, Rayman was the front page picture, and it was notable enough to get some small degree of coverage by the gaming media.
I do agree this trophy is weird, but if you think about it, there's a lot better you could say. Rayman Legends was a pretty significant early "exclusive" for the Wii U, and while I doubt Nintendo is super happy with how Ubisoft handled it, Ubisoft has nevertheless still probably done more for the Wii U than most other major publishers (Child of Light also had a Wii U release). Ubisoft likely wanted the free advertising for their game in smash, and it's just good business from Nintendo to give them a nod like this. Something like a playable character would require some serious business dealings neither company may want, but it's not exactly legally difficult for one company to gift another a small bit of advertising. Heck, that PotD post may have been a bigger part of the deal than the trophy being in the final game itself; for 24 hours on the smash 4 site which gets a ton of hits, Rayman was the front page picture, and it was notable enough to get some small degree of coverage by the gaming media.