You might be tempted to swap out Kotis for Muldrotha, and there is merit in doing so, but you can always bring Muldrotha back turn after turn with Kotis, and eventually, Kotis will outscale Muldrotha in terms of power once you cast two creatures from your graveyard, and will only keep growing
Even better, you can use most of your existing Pokemon TCG cards with Pokemon TCG: Rumble or you can buy Pokemon trading cards in booster packs to expand and add new strategy to the game
While action cards are the easiest of the cards, they can truly transform a play at short notice
Putting mana rocks in your deck isnt difficult, though, and thats before we talk about things like Basalt Monolith
That said, players can vote against this, especially if they'll lose important cards, so at least you can plan your game around getting two important cards back