Grumpig

Grumpig's good HP and Special Defense stats in conjunction with Thick Fat allow it to take on a lot of Fire-, Ice-, and Psychic-types like Ninetales, Cryogonal, and Mr. Mime. A wide movepool gives it access to many tools like Thunder Wave for offensive teams and Taunt and Toxic for taking on stall. It also has access to Shadow Ball and Focus Blast, giving it coverage against other Psychic-types like Mr. Mime and Dark- and Steel-types like Pawniard and Probopass. Unfortunately, its less-than-stellar Defense leaves it with a weakness to physical attackers like Dodrio and Leafeon on top of being weak to Dark-type moves, which are fairly common. Grumpig also does not possess any reliable recovery, meaning it can get chipped down pretty easily and relies on Leftovers to gain any HP by itself. Nonetheless, due to the number of positive traits that Grumpig possesses, it isn't very hard to stick on teams, especially when looking at the number of Pokemon it can check regardless if it runs its offensive set for balanced and bulky offensive playstyles or specially defensive set for stall and semi-stall.