Gardevoir+Dedenne ex

Try adding some stadiums. Path to the Peak kills the deck.

maybe add natu and xatu from paradox rift, there seems to be a lack of draw power in this deck

There is one major flaw in this deck: Gardevoir ex can only attach energies to psychic Pokémon, and since Mewtwo is a lightning Pokémon, you can't damage it in any way. Also, add add in four copies of Kirlia from silver tempest, it's refinement ability will be key to finding the cards you need while getting energy in the discard. It'll also give you another way to get Gardevoir into play when you don't draw your rare candies

Sorry to comment twice in a row, but I think another thing that might help you is Kirlia from chilling reign, which searches for three Kirlias from your deck and puts them onto your bench. This, when paired with Silver Tempest Kirlia, will give you a much stronger setup when you miss rare candy.

Alright, I'll shut up now. Feel free to ignore any of my suggestions if you want, I mainly just wanted to make sure you knew about Gardevoir only attaching to psychic Pokémon 

I fixed the gardevoir only attaching to psychic types issue. Just attach the entries to Gardevoir instead. They don't all need to be attracted to Mewtwo to attack. Also added the kirlias. I appreciate the feedback from everyone:). I'm new to deck building. 

I made the same mistake with Gardevoir only attaching to psychic types with my Gardevoir Dodrio(151).

Maybe add either a 1-1 line of Mimikyu Vmax with a couple of Acerola's Premonitions OR playsets of Iron Valiant and Future Booster Energy Capsule(to fix the math on higher HP Pokemon for Dedenne)? You could even play Hatterene Vmax for its ability and sometimes confusion. To save space, you can replace mewtwo ex AND xatu with 2-2 Shadow Rider as an attacker and accelerator. Keep in mind of liabilities of gust KOs though. Probably lose the articunos, but it could be good bench snipe, even though manaphy blocks. NEEDS MORE POKEMON SEARCH.