252 HP, 252 Sp. Atk, 4 Def, Modest Nature, if you want to deal damage with your Meowstic.
252 HP, 252 Def, 4 Sp. Def, Bold Nature, if you're looking to only set up screens and then switch out. If this is the case, I would give your Meowstic T-Wave/ Toxic > Psyshock/ Shadow Ball.