Original creator of mega Diance deck. Currently Top 500 with it. 64% win rate last season. You can play PCL or Cyrus instead of sabrina, but I found sabrina to be most consistent. I recommend 2 giratina since getting early for energy generation is crucial. I provide extensive detail on how to play most match ups in the origianl reddit post in the original reddit post.
Espeon ex & M Diancie
Endure your opponent's attacks with Espeon ex & Sylveon, all whilst charging up M Diancie and Giratina ex. When set up, inflict pressure with Espeon ex before dealing the final blow with M Diancie.
Note that the stategy can change according to the board state & matchup.(edited)
Small Baloon gave this deck a slight buff. I was experimenting with the new dragon support + juggler but it felt inconsistent, so I just went back to the old variants.
Ensure Ho-Oh doesn’t get KO’ed in the active, sustain it with Ice Pops. Once you Phoenix Turbo energies onto Terapagos, use Small Balloon + X Speed to free retreat, then Juggler the energies from Ho-Oh and Giratina to Terapagos. Play Grass, Dark, Metal/Fighting energy to get up to 200 damage with Terapagos.