IMO outpacing base 145s (Mega Beedrill and Sceptile) at plus 1 with a spread of 8 HP / 252 Atk / 248+ Spe or at the very least Mega Lopunny (and mega manectric but mainly mega lopunny) with a spread of 56 HP / 252 Atk / 4 Def / 196+ Spe is probably the most optimal unless you're really going for...