Articuno-GX has a lot of potential in water box, when combined with Cyrus.
You can eliminate a lot of offensive momentum by swooping in, removing all their actives energy, and shuffling their bench into their deck.
Not to mention, Articuno has support as an attacker through things like Water Patch and Max Potion.
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I'm not understanding the hype for Salamence-GX, however.
Very linear card.
Retreat cost ability doesn't work on a lot of cards it would want to be paired with, and Salamence doesn't do enough on it's own to really warrant a slot; when you could just put a switch/guzma/dawn-wings.
[R][W][C][C] for 200 damage on a Stage2... is just... clunky.
and the GX attack is basically: [R][C][C] for 120, which is super underwhelming.
Entei-GX is more consistent, and has a better GX if you want to snipe.