>>16097640
The biggest difference is that Yo-kai are treated as your friends rather than your slaves. They're not contained in a little ball you carry around at all times - they have lives outside of being used by you in battle.
More importantly for gameplay, this means you don't have direct control over them like Pokemon. In battle, your yo-kai do what they damn well feel like, and your job is to keep them healthy and occasionally power them up. Battles take place in realtime and are a lot more fast-paced and arcade-like than Pokemon. You need to react quickly to switch yo-kai in and out of battle as they get injured or status ailments, and play short microgames (tap all the things, spin a wheel, etc) to heal them or power up their super moves.
The world feels a lot smaller than Pokemon - 90% of the original game takes place within one single town. The second game adds another town (and the ability to travel across Japan by railway, although in almost every case you can't leave the train station at any of the stops except for the two towns). However, those two towns are huge and absolutely packed with things to do.
The game is a lot more story-driven than Pokemon. It's structured episodically, where there's a main conflict/enemy to be resolved each chapter (with lots of sidequests), but there's a main overarching plot. The stories are generally stupid/funny but with some feels.
Apparently, Yo-kai watch 3 changes the formula up a lot and is far better than the previous two games in terms of gameplay, but my copy hasn't arrived yet so I can't go into much detail. Looking forward to it though.
One thing it has in common with pokemon: lots of cute lolis. Some of the yo-kai are pretty sexy too, even if you're not a furry.