The Play! Pokémon rules and regulations are periodically reviewed to maintain competitive balance in the Championship Series. The documents have been updated to reflect the latest review in summer 2019. Pokémon TCG and video game players and Professors are encouraged to familiarize themselves with the latest rules and regulations ahead of their next competition. According to the updating documents, Mega Rayquaza and Dragon Ascent have been banned from VGC.
Source: Pokemon.com
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