So i played about 17 matches. And my deck did fairly well considering it only has Mewtwo EX in it and i played against tons of EX based decks. Roughly like 12/5 was my win/loss ratio. Though i had a few matches with just zubat on first turn or running into no energy for 8 turns.
Though i did find that this deck is terrible in 4 player double battles. Its too slow and it didnt end up doing anything.
As for the deck itself, While it still needs some work and maybe another crobat.
Pokemon: 17 (11 Basics)
2x Giratina PS
1x Mewtwo EX
3-1-2 Crobat PS (2 Spiral Drain and 1 Free Flight)
1x Trubbish NV (Garbage Collect)
1x Garbador DRX (Garbotoxin)
2-2 Garbador PS (Biosmog)
1x Mr Mime PF
1x Sigilyph DRX (Though i added it in after league and took out a zubat)
1x Colress (Would rather change it for N or Juniper though)
1x Pokemon Communication
3x Great Balls
2x Virbank City Gym
1x Float Stone
1x Rescue Scarf
3x Rare Candy
4x Hypnotoxic Laser
1x Tool Scrapper
1x Superior Energy Retrieval
1x Dowsing Machine (Ace Spec, though i might switch for comp search)
3x Double Colorless
Overall the plan of this deck is to assemble crobats as soon as possible for the night sight extra draws as well as easy 80 damage without Virbank, and either force a switch or get a knock out next turn. Giratina is there to deal with other psychic pokemon as well as destroy the opponents hand with its shadow claw. Mewtwo is well mewtwo. Mr Mime protects your bench against the likes of articuno EX, Landorous EX, and Darkrai EX to name a few. Sigilyph blocks all EX attacks and can smash things that stack energy, like Keldeo. Garbador with biosmog both poisons as well as discards precious plasma or double colorless energy with a coin flip. The garbotoxin garbador uses rescue scarf or float stone to cancel all abilities and can be stripped of it if desired with tool scrapper.
I find great balls to be more helpful than level balls or plasma balls. They may not be able to grab what you want when you want it. Though it can pick up any pokemon from the top 7 cards of your deck, which as i found out at league, is really helpful and often got me something. Running as many junipers, its nice to be able to pull out stuff from my discard using trubbish or dowsing machine mid to late game. Though computer search is more helpful early to mid game. I like to carry at least 1 switch incase something gets stranded or paralyzed. Energy Retrieval is really useful, though hard to fit into my deck, so i only added one superior one just in case.
Interesting things I realized while running night sight is that it really allows you to work/play around with your supporters. Being able to draw 2 extra cards to see if you really need to juniper a precious hand or drawing after juniper to pick up a few extra cards can be game changing. It could also work well with Pokedex as you can choose what cards from the top 5 of your deck to draw.
Note that this is in no way a professional deck, and it does have some kinks to work out, like needing another crobat. Though it can perform well against decks that heavily rely on abilities, EXs, or large retreat costs.