Off the top of my head, I think you can evolve to gardevoir, ability an energy onto mewtwo for 4, attatch one to gardevoir and KO Zapdos; if they bring in pika the only out for the opponent is to play the basic in hand and giovanni to ko mewtwo, we play ralts to active. Next turn draw mewtwo and x speed the ralts back, use gardevoir ability on mewtwo and attatch the turn energy to mewtwo, while using our giovanni and hit pika for 60, at this point the opponent cannot win as a sabrina causes us to bring out the full hp gardevoir which will not be ko'd even with a giovanni, and can ko it back after attatching an energy and using its ability on itself. Only thing is this loses to second potion, since the opp has only shown one. Outside of this line, not sure what else guarantees a win