>>29480271All three of them will be around UU, and usable in OU.
Decidueye has a signature muhmentum move in Spirit Shackle, so it can deal damage while controlling switching.
Incineroar is the fastest and strongest of the three, and it's already going to be better than Houndoom which it shares a type with.
Primarina is guaranteed to be good solely because of its typing + Scald. It's the bulkiest of the three so that works out.