I think 1 through 8 aren't fun at all. Boring and predictable. If anything it's the opposite of fun. 200+ pokemon in the game so far and you face the same 8 at virtually every and all gyms.
I don't see a lot of slowbro as it's just not in the same tier as the previous 8.
Fun? Anything out of the ordinary. The 200+ pokemon that don't just get auto-placed in gyms. Granted, the ones you listed are boring because they are generally the best gym defenders. But I've almost become blind to their actions and animations as I see SO many of them in gyms.