RogueChomp, It's not that hard (I 6-0'd one at my last cities with Darkrai/Landy lol)
For starters, get a quick night spear. T2 Spear REALLY helps out and can just straight up win you the game right there. From there, just make sure you set up Darkrais and use Mewtwo very often. VERY often. Keldeo despises Mewtwo in every way, shape, and form, just troll the hell out of them with it. My Darkrai/Landy list runs 2 Mewtwo and 2 DCE, which really helps, but it's still possible even if you don't run those. If they only get 1 Blastoise up and have a slow start, you can snipe it with Spear twice and then KO it, but don't do it unless it's clearly the best option.
Edit: Also if you feel like it you can use Landy + Energy switch to finish the game with 150, but only do that if you can win that turn or you're sure that they don't have a catcher (or if they win anyway if they get a catcher)
For starters, get a quick night spear. T2 Spear REALLY helps out and can just straight up win you the game right there. From there, just make sure you set up Darkrais and use Mewtwo very often. VERY often. Keldeo despises Mewtwo in every way, shape, and form, just troll the hell out of them with it. My Darkrai/Landy list runs 2 Mewtwo and 2 DCE, which really helps, but it's still possible even if you don't run those. If they only get 1 Blastoise up and have a slow start, you can snipe it with Spear twice and then KO it, but don't do it unless it's clearly the best option.
Edit: Also if you feel like it you can use Landy + Energy switch to finish the game with 150, but only do that if you can win that turn or you're sure that they don't have a catcher (or if they win anyway if they get a catcher)