As just announced in the January Nintendo Direct Mini, Pokkén Tournament DX will be receiving two waves of Paid Downloadable Content
Wave One goes live on Janurary 31st and will include new playable Pokemon Aegislash with Mega Rayquaza and Mimikyu as the first support set.
Wave Two goes live on March 23rd and will include new playable Pokemon Blastoise with Mew and Celebi as the second additional support set.
The "Battle Pack" which includes both waves of DLC is already available for purchase on the Nintendo Switch eShop for £13.49/$14.99/€14.99 and will unlock new clothing options for your trainer and for Nia. With the Battle Pack, you'll receive the content immediately upon their respective release dates like other DLC "Season Passes".
The Direct Mini itself can be watched in full here
Writers note: It's not yet known if the wave one DLC will be usable at the Syndey Worlds Qualifier. Be wary.