>>55667363for reference, the tri Psystrike matchup. mewtwo is not a pokemon that sims well, especially since a lot of times PvPoke wants to throw the coverage move when it should just be psystriking.
Your coverage move is only used in extremely specific situations. Shadow Ball vs Lugia/solgaleo/Metagross, Ice Beam vs Zygarde-C/Lando or the odd Zarude. Basically if Psystrike is double resisted, your coverage move is probably better, or if your coverage move is double SE.