The possibilities of Latias EX

I got a booster box of PTCGO codes, and got 2 latias EX. I realized how good its ability might be in this metagame

Ability: Bright down
Prevent all effects of attacks, including damage, done to this Pokémon by your opponent's Pokémon with Abilities.

This would mean Trevanent, shiftry, darkrai EX, boufallant, greninja, Genesect EX, Virizion EX, Keldeo EX, and even Pyroar would not even be able to touch it

Meanwhile it would even be able to attack Pyroar back.
It seems like a great wall, but would lose to Darkrai and mewtwo EX in a heartbeat

(Garbador can be countered with some startling megaphones)

It seems like a really good card... what am I missing?

How to get energy onto it consistently. You'd need to run cards like Professor's Letter to ensure you get both types of energy. That or some of the Blend Energy cards.

It's also got very low HP for an EX, and can easily be taken down by Mewtwo EX or Yveltal EX.

Well, that and its comparatively weak attack, which does a flat 70.

I guess rather than attacking, it would be a good wall Pokemon when necessary with a low retreat cost. Throw in a skyarrow bridge and it has none.

I wonder how it would fair in a pyroar sigilyph deck....

With 160 HP? It'll get wrecked by a lot that's out there.

Still has some potential and you should give it a go, though.