Let's chat about Mewtwo V-Union in the new format!
Mewtwo List
I've always had a fascination with making the V-Unions work.. but prior formats haven't had the tools we currently have with the release of Brilliant Stars. There are two cards that stick out in my mind with Brilliant Stars as being supreme enablers of the V-Union Strategy: Ultra Ball and Arceus VStar. Ultra Ball is so good for a number of reasons - first, you can discard your V-Union pieces MUCH easier now that there's Quick Ball, Ultra Ball, and Research to do so. Second, Ultra Ball can find your V-Union pieces making it much more realistic that you can get them into hand when you want them. Prior to Ultra Ball, the only ways to search out V-Union pieces were with Adventurer's Discovery and Prof. Burnett... both not particularly strong options.
Arceus is what really brings the V-Unions viability in my mind. With Arceus VStars Starbirth Ability, fetching those Pokemon V-Unions from your deck is easier than ever. And it doesn't cost you your Supporter! Arceus is such a strong card for the V-Unions not only for the searching effect, but also because it can power up those Pokemon once they come into play. Sweet.
In building this list, I needed to make sure I didn't sacrifice everything in the deck toward making the VUnion work. At worst, this is a control style Arceus deck with the option to play Marnie + Path at any time to lock the opponent down. It also runs Big Charm to beef up your Arceus and make it even harder for opponents to KO. There will absolutely be times where you prize a piece of the V-Union puzzle and we'd rather not scoop in those instances. Things we could have added at the risk of watering down the core Arceus concept might have been Peonia, or more Adventurer's Discovery, but it just didn't feel correct to bend over backwards for the V-Union. If it happens, awesome and if it doesn't, you still stand a reasonable chance.
4-4 Arceus is essential in this regard. I know it might hurt for your wallet to hear, especially if you're still playing in PTCGO, but it's the truth. In order to be able to shift to an Arceus only strategy, it behooves us to play the maximum count.
Why do I like the V-Union and not some other attacker? Well, it's fun first of all...Who doesn't love pulling out a wild combo? I love it especially when I can put every piece in the discard pile in one turn so that my opponent has no idea what's happening and then all of a sudden they are threatened with a massive V-Union dealing out 330 Damage a turn. The math on Mewtwo's attacks are quite relevant - the snipe of Psyplosion is amazing for KOing any single prize Attackers and Final Burn with a Choice Belt KOs just about every V or VMAX in the game. You really can't go wrong with such good coverage against both single and multi-prize attackers.
Overall, this deck struggles when you can't get Mewtwo up and running, but has a great time when you can. Here are my ratings for the deck via the FlexDaddy Playability Index:
Viability ⭐⭐⭐
Longevity ⭐⭐⭐⭐
Portability ⭐⭐⭐
Novelty ⭐⭐⭐⭐⭐ Affordability ⭐⭐
Enjoyability ⭐⭐⭐⭐
This deck feels somewhere in the low Tier 2, high Tier 3 range. It's explosive power once it comes alive can overrun just about any deck, but the awkward clumsiness of prizing key pieces or missing a T1 Energy drop are too hard to overcome in most instances. Hopefully we can get some more pieces in upcoming expansions to make this deck even better!