What would you want instead, and please don't tell me the burning attack
Fireball was actually a decent attack in the PAL version. It traded with sword slashes (both players damaged) and ploughed through projectile spamming.
But I'm not really that fussed what Yoyo Spin's replacement is. I quite liked Breakstand too. It was short and sweet.
That's what I'd be going for. Something fast or cancellable with an exciting or comical look to fit in with the character's Smash representation.
Breakstand did the comical side, with an almost clumsy use of his dashing momentum taking him into a handstand. Fireball did the exciting visual effect, fitting in well with the likes of his Stone transformation and Final Cutter's projectile.
Yoyo Spin, IMO atleast, had neither the clumsy/childish aspect nor anything to set it apart from something any other character might do. I get that it's a traditional Kirby move but there are so many better ones in his games. Furthermore, from a gameplay perspective, it required a lot of commitment. It was long and had no way out nor any way to control it after it started.
If I wanted a slow, multi hit, spinning move, Kirby's F-air was vastly superior anyway. More knockback, more damage per hit, less time wasted if it didn't connect and, best of all, mobility.
I'm sorry but I really do not like that move and would prefer just about anything to it.