Luvdisc from Crown Zenith, Jirachi from Paradox Rift, and the Piplup from Legendary Treasures are all great starting points
Orcish Bowmasters is a great card for this deck (or any deck with black in the color identity), and can potentially double your army's growth rate while whittling down your opponents
With this move I wish Mewtwo's retreat cost wasn't so high because I would get the defending Pokemon asleep as fast as possible then move in a Pokemon like Snorlax who has moves that does more damage if the defending Pokemon is asleep, if somehow I could get retreat costs to be much lower for all Pokemon I would switch back and forth between Mewtwo and another card quite rapidly
Dont just cast Teferi and pass the turn unless you have a hand full of (free) counterspells
A dream would be to have Necrogen Communion on one of those two, then hit it with Saw in Half
Anyone familiar with the antics of Clifford the Big Red Dog will immediately understand the idea behind Mowu: hes a Dog, and he gets very big, very fast