I have been testing a Mewtwo-based deck, which does actually work pretty fine.
2-2 Mewtwo Lv.X
3-3 Arcanine SW
2-2 Claydol
1-1 Azelf Lv.X
1 Rayquaza
1 Regice
(1 Unown G)
The combo is Regice discarding energy and switching staller basics out of the way, Mewtwo picking it up and either using it itself or letting Arcanine come and throw a big hit. You can usually pick up 4+ energy before your opponent starts getting anything significiant out, and when he does, just blast them with Arcanine and follow up with Mewtwo to take another one of their big hitters down. I have pretty strong focus on PlusPowers and Bucks so that I can take down 95% of the current pokémon with one hit. Rayquaza provides an alternative method on charging Arcanine. Still, Mewtwo is the main attacker.
Also, self-charging, 120 HP (140 with Snowpoint), 120-hitting, no-weakness (with Azelf Lv.X) and no-effect taking (with Unown G) pokémon which doesn't even take damage from basics can be quite a pain to take down, true? And just a reminder: When you're not in danger, use the MD Mewtwo's Psyburn for 2HKOs or even 1HKOs. And if your opponent stalls, you can even Recover your Mewtwo.
It's not as bad as people are making it to be.