My Mega Metagross list inspired by current Greninja and Mega Sceptile/Blaziken lists. Aegislash solves Metagross' problem of dealing low damage unless ramped and makes Kartana and Metang both dangerous attackers. If energy feels like an issue I reccommend replacing Kartana with Wynaut and/or a copycat with a second Wally. I like it as is for the consistency and Metal Core Barrier can allow Kartana to survive an extra turn.