Xerneas 107/162 has an amazing second attack, and when combined with potion or a Pokémon Center Lady, the effects can be awesome.
This attack is one of my favorites. It does 10 damage plus 30 more damage for each different type of Pokémon on your Bench. This can be combined well with Pokémon Fan Club, which pulls 2 basics and benches them. If you plan to use this attack as your main one though, you should consider sky field, to put a bunch of Pokémon on the bench. Dedenne from Furious Fists can also be really helpful. It not only is a different type, but it can fish out more basics of different types.
This attack is kind of cool, because it relies on being healed. A good match up with this attack is Jynx, who heals 10 from your active each turn. If you can manage to get 1 of them on the bench, you can do some serious damage. Potion and Pokémon Center Lady also work really well. You can do up to 180 damage per hit. A good idea is to use Florges and Florges-BREAK from XY-BREAKthrough to decrease the number of energy needed to attack and to heal your Xerneas each turn. Wonder Energy can really help as well, because it prevents special conditions from effecting your fairy Pokémon, but if you are running a Florges-BREAK, you don’t really need to.
To really make a deck with this, you should run a lot of different basics, especially ones that aren’t colorless, but require only colorless energy.
I rate this card a 3 star.