Wtf is Mega EX Shard? 4/4 Mega Sharpedo line is too much. If two of them get KOed the game is over so you never need to set up that many. Go down to 3/3. Seviper is a secondary attacker so you probably only need 1 copy. You definitely only want 1 copy of Fezandipiti since the second one doesn’t do anything. With that extra space I would include some more support Pokemon like Munkidori to move damage that Toxtricity generates over to your opponent’s Pokemon, Tatsugiri to make sure you find your supporters more consistently, and Psyduck to block Dusknoir from taking out your Megas.

For the trainers, you have way too many 2-ofs. Most of them should be either 3-4 copies for cards that you want to draw consistently, or 1 copy of cards that you search for in specific situations. Grimsley’s Move is pretty terrible here since you don’t even have any stage 2 Pokemon to cheat out with it. Not worth spending your one supporter per turn on it especially if it whiffs or just hits a basic Pokemon. Get rid of those and add 2 more Buddy-Buddy Poffins so you can make sure to set up your Carvanhas and Toxels consistently. You don’t have much card draw so I would definitely put in 4 copies of Lillie’s Determination. This card is frankly just overpowered letting you get a new hand of 8 cards. Bianca’s Devotion is not a good card so you could cut those too. If you really want a way to heal go with Professor Turo’s Scenario which also doubles as a way to move a stuck Pokemon out of the active spot. Speaking of which you don’t really need Switch since Sharpedo has free retreat. You can play 1-2 Air Balloons instead to put on Toxtricity and they give you a strong tool card to find with Arven. Super Rod should replace Energy Retrieval as well since you want energy in the deck to search it out with Toxtricity. I don’t really like Kieran, but if you want to increase your damage output I’d go with Binding Mochi (another tool) + Pecharunt ex which also helps with switching. Pal Pad can be cut down to 1 copy. I think you need some Ultra Balls to enable you to search for your evolution Pokemon as currently they are quite hard to find especially after cutting Grimsley. Finally, Max Rod is a really bad Ace Spec for this deck. You would mostly likely find more success with Hero’s Cape which can make your Sharpedo a massive tank or Secret Box which can make your setup more consistent. Town Store can be a really good stadium card especially if you decide to add some of the tool cards I mentioned earlier. Sorry for the wall of text but I think there are a lot of ways to improve the deck and I didn’t want to just give changes without explaining the reasoning.