Yep! As speculated from Sonic’s amiibo being supported in the game, as seen above, it is so, Yoshi will get to be blue but not so spiky!
The image came from a video by ODDERZ Plays showcasing most of the amiibo skins for Yoshi, including the Inkling Squid which just came out of course for Splatoon (only that one was shown, since its the only of the three he has, so I assume the Inkling Boy and Girl ones work also), I would assume Chibi-Robo will also be included who is only available I believe in a bundle with Chibo-Robo: Zip Lash on 3DS. Bad news is, no Pokemon will give you their skins, they’ll give you unrelated patterns, but no Pikachu Yoshi for you sadly. 🙁
Check out the vid below, the amiibo line-up starts at 4:07 and Sonic Yoshi shows up at 5:35:
Pic was taken by GoNintendo.