I am in the EX world. I have beaten the first three battle arena stages. The trouble is the last one is just so challenging. For stage 4-1 I use Mew w/ Poison Jab and Thunder, Electivire with Cross Chop and Psychic, and Zapdos with Thunder and Drill Peck. For stage 4-2 I end up using Machamp with Cross Chop, Skymin with Seed Flare and Protect, and Staraptor with Hyper Beam. I have gotten really close to beating it. I also have one Shiny Pokemon so far.
FC: 1778-9489-4489 IGN: King Arceus
Safari: Ferroseed, Klang, Bronzong
VGC 2015 Season: 166 CP