tbh I haven't used any set besides SD once, so idk how Pain Split would work. It sounds like a healthy dose of offensive and defensive pressure, especially if you play early with Intimidate Mawile. I actually haven't used any Megas outside of Manectric (oh god I love Electric-type pivots ever since Lanturn last gen), Venusaur, Medicham, and Charizard X, so I should probably expand to other stuff.