the last few month, the theme deck metagame was basically only the latest 2 decks that came out with Crimson Invasion.
subjectively percieved winrate:
Destruction Fang: 70%
Clanging Thunder: 90%
all other decks: >20%
With Clanging Thunder beeing the most played deck, by far.
Destruction Fang has the best card draw so far, and having a wishful baton is basically a 1-price advantage over decks that don't have that card.
That said, it has got a huge weakness against fighting.
Gastrodon and Solrock from Clanging Thunder destroy 50% of the Destruction Fang mons, sadly.
Clanging Thunder simply wins any match by having an infinite number of heavy hitters that are able to swing for 120 or more damage.
Also, it's got kinda nonexistant weakness such as grass and fairy type, which are not played competitively, altho there is a sylveon deck including both, but the old pre-powercreep decks have no card draw and lots of unusable mons.
Now, with UltraPrism (Us/Um), we get 2 new decks that seem to be able to overpower Clanging Thunder and Destruction Fang by far.
(the decklists are already out on bulbapedia)
With Mach Strike, we get the Champion Combo with Garchomp, Lucario and Cynthia, means extreme tutoring, extreme card draw and extreme damage output (200 damage) that basically oneshots everything, with Pal Pad allowing up to 4x Cynthia play for the 200 damage Chomper.
With Imperial Command, we get alot of energy control and mons that have 0 energy attacks, which is amazing tbh, because it allows for faster surprise plays when a 0 energy mon on your bench suddenly has 4 energies while you attack with your active mon for 0 energy cost. That said, the damage output will not be enough to overpower Mach Strike.
Alolan Sandslash seems like the best card in this deck, dealing damage for free while at the same time forcing your opponent to take a risk of reflected damage, or skip attacking which gives you a free turn to chip in some more damage.
Both decks come with a good/accetable trainer pool featuring much card draw and escape/switch potential to break free from para/sleep, with Mach Strike having the better trainer pool due to the malasada and pal pad. 2x pokemon fan club in Imperial Command seems like a waste of potential. Especially when you already have 10000 pokeballs tutoring your mons. The fan clubs are just not necessary.
So much for the analysis.
What actually baffles me is the contiunation of power creep in Theme Decks.
Yes, it's nice not to have 30 minute matches due to bad card draw and low damage anymore. I love that they finally realized how important card draw is.
On the other hand, there is no real metagame anymore.
You can play either of the 2 newest decks and that's everything there is if you want to #1) have fun and #2) win.1 deck is always having an advantage, but both decks are overpowering all the other, older decks. (unless you get really unlucky and draw only energy, but that is not the standard anymore thanks to good card draw, and thus should not be weighted in a comparison of theme decks anymore)
Thanks for reading.
Specialized on Theme Deck Tournaments.