Your recovery is your biggest weakness in doubles. It's not hard to juke one opponent, but if there's 2 people edgeguarding you, you can't avoid them both. It's a workable problem, but it's tougher because you need to rely on your teammate to back you up by running interference. Yoshi also can't really be saved by his partner, because getting hit isn't gonna give you a jump back.
Outside of that, Yoshi is a strong character. His strengths will still be there, for doubles. Kinda like Falco, ya know? Struggles offstage, recovery gets worse, but he still has a great onstage game. Unlike Falco, you don't have quite as amazing a projectile, since you can't throw it out at will.
Overall I'd say Yoshi isn't ideal for teams, but if he's the character you play, he's not unviable. If you've got other characters, I'd probably use them, but only if they're as good as your Yoshi.