Uxie

At first glance, Uxie appears to be entirely outclassed by other Psychic-types such as Mew and Tapu Lele. However, Uxie's combination of Trick Room, Stealth Rock, and Memento gives it a defined niche on Trick Room teams, as it's able to compress roles very efficiently by acting as a Stealth Rock setter and Trick Room setter while being able to provide its team members valuable momentum with Memento. Uxie's fantastic defensive stats also allow it to survive almost any hit and set up Trick Room in most scenarios. Despite this, Uxie is only viable on dedicated Trick Room teams, as it's completely outclassed by other Psychic-types such as Cresselia and Slowbro on any standard team. Uxie is also extremely passive, as it's unable to do much damage because of its pathetic offensive stats and because it usually can't afford to run an attacking move. It doesn't help that dedicated Trick Room teams are generally questionable in regards to viability and consistency, often considered just a gimmick.