Mesprit

Mesprit has middling attack, middling defense, and middling stamina. While it's not necessarily terrible, it's not particularly exciting either. Higher Psychic-type DPS than Lugia, but lower than even Confusion/Psychic Gardevoir. If you have access to Alakazam or Espeon, I have a feeling you'll want to leave the Emotion Pokémon on the bench.

Best PvE Offensive Moveset

• Confusion is the superior fast move on offense.
• Extrasensory falls behind, but not by much. 
• Future Sight benefits from STAB and is Mesprit's highest DPS moveset.
• Blizzard lacks STAB and doesn't suit Mesprit's role. 
• Swift lacks STAB and can't be Super Effective vs anything.

Confusion sports significantly stronger damage output than Extrasensory, though the latter generates energy slightly faster. 

Swift is Mesprit's cheapest Charged Attack, padding up its otherwise clunky moveset, but it isn't very strong. Blizzard costs the most amount of energy, but provides useful coverage and can also deal significant damage if unshielded. Future Sight benefits from STAB to threaten considerable damage, but demands a lot of energy to use and doesn't provide coverage.