Whenever a new set is released, it becomes playable in official events two weeks after its release. This means that, as of October 22, Celebrations (and the CEL Mew) is officially tournament-legal. And if you’ve paid attention to the metagame, there’s an important question you might be asking: who cares?
Like most sets outside of the main series (Champion’s Path, Shining Fates, etc.), Celebrations is not very remarkable from a player’s point of view. It’s a wonderful set for collectors, and even as someone who cares about the actual game more than any other aspect, I can’t deny that most of the cards are gorgeous. Mitsuhito Arita’s Zacian V and Zamazenta V are so much more dynamic and impressive than 5ban Graphics’ illustrations! I do wish that the list of Pokémon worth celebrating wasn’t limited to legendaries and Pikachu, but that’s another topic.
However, if you’re looking to get these cards to play them, you’ll be disappointed. They aren’t terrible or anything; Lunala and Yveltal have interesting attacks, for example, and control players are happy to see Dialga’s Temporal Backflow. However, I don’t expect any of these legendary Pokémon to have a real impact on the metagame… except maybe one.