This has very powerful synergy, even better in expanded as others have said.
So second garchomp attack if we play Cynthia that turn we deal 200 base, with one altaria drx and choice band we hit that 250 that everything is koed by atm. Standard and Expanded have multiple ways to grab the Cynthia so we can use it turn after turn.
Only problem I see is a 2-2 (3-3) lucario line and 3-2-3 (or similar) garchomp line (and 2-2 altaria in expanded) line uses up a lot of deck space before considering staples like 2 or 3 lele gx, alolan vulpix, etc, so a lot of testing is needed to find the right ratio for it to get setup quickly.
still from the cards shown so far I can see garchomp and various metal decks becoming big, depending on which wins out gardevoir gx may still have a place as it can easily ko garchomp with weakness.