Grumpig

Although Grumpig seems outclassed by its fellow Psychic-types, it does have some advantages over them; Grumpig has higher Special Attack than Uxie, while Thick Fat allows it to take on Fire- and Ice-types much more easily, which is especially helpful as UU is filled with Pokemon such as Moltres, Blaziken, and Arcanine. Grumpig also has decent Speed, and excellent Special Defense and HP. This makes it a great supporter, which is further reinforced by its support movepool, which includes moves such as Taunt, Heal Bell, Reflect, and Light Screen. Unfortunately, Grumpig's average Defense doesn't help its Pursuit weakness at all, and its lack of recovery outside of Rest is disappointing. Overall, Grumpig is a decent defensive Pokemon, making it usable on stall teams and those with plenty of entry hazards.