Mesprit

Mesprit stands out as by far the most versatile Pokemon in PU thanks to its solid stat distribution, excellent ability in Levitate, and wide support movepool with moves such as U-turn, Healing Wish, Trick, Nasty Plot, and Stealth Rock. Mesprit is extremely good at role compression and can fulfill a variety of different needs for your team, although its counters rarely differ too much based on the set. While Mesprit is a solid wallbreaker and has the speed to beat out slower offensive and defensive staples like Perrserker and Weezing, it's still outpaced by a large portion of the metagame. Combined with a lack of any reliable recovery, this gives Mesprit extreme longevity issues, particularly Choice Scarf sets, which will rarely outspeed any other boosted Pokemon. Furthermore, Mesprit's special coverage can be lacking at times, as Mesprit can struggle against Steel-types such as Aggron and Togedemaru. Ultimately Mesprit's role compression can be very useful for covering weaknesses, but Mesprit will never be the best at any one role it attempts to cover.