Mesprit

Mesprit is the classic example of a "jack of all trades, master of none." At a first glance, Mesprit's good stats and wide movepool might make it seem like a powerful and reliable utility Pokemon. And it is, to a certain extent. The problem with Mesprit is that there's usually another Pokemon that does what it does better. In particular, Mesprit faces stiff competition from three other small and cute Psychic-type fairies: Azelf, Uxie, and Mew. Azelf is far better suited to offense, Uxie is a top-notch defensive Pokemon, and Mew's higher Speed, HP, and nigh limitless movepool make it the superior choice in many occasions.

However, Mesprit does have its perks. Its access to Healing Wish and lower Speed than the other Psychic-types make it a fantastic Trick Room supporter. Similarly, a Ground-type immunity, courtesy of Levitate, gives it another way to distinguish itself from Mew, which for the most part runs sets that don't clash with Mesprit's. If you make sure that Mesprit isn't outclassed by its brethren, the little sprite will undoubtedly serve you well.