Mewtwo is tough. And new episode!

Mewtwo is easy to beat but really tough to recruit. I was even holding one of the 7 treasures and I was level 66 and he still didn't join. Any tips? I am getting him in explorers of time because of the Wi-Fi missions that unlocked Mewtwo in time and Celebi in darkness. So I am gonna keep trying! Also check out the new episode tomorrow and 9:30. Cartoon Network. Should be cool.