Zek/Eels can easily beat Quad Terrakion by going aggro Mewtwo-EX with Eviolites attached. This is so they cannot two-shot Mewtwo, and so they can't one shot your Zekroms and Zekrom-EX's. Since they'll be keeping energies attached with EXP share, you will pretty much get free fuel for X-Ball, leading to quicker KO's and a quicker win.