Thankfully, with Wilds of Eldraines Enchanting Tales containing powerful white reprints like Land Tax and Smothering Tithe, Moonshaker Cavalry should have all the support it needs to have maximum impact and regularly close out games
I remember having to face one of these in an AD&D campaign(2nd Ed)(yes I'm old), it killed 4/5 party members and most of the elite squad we had helping
So if you can evolve into Shiftry on the first turn and you hit heads and shuffle your opponent's only Pokemon into their deck, then they lose automatically
For example, even if we interpreted your library as part of the battlefield for this purpose, slipping one into the card sleeve of a card in your library during a search effectively marks your deck, and thats not allowed
Maybe focus more on the combo aspect of the deck, or maybe deal more damage