>>714785589
You could literally use any card in the game because it has a feature that lets you use cards from other players, but it's limited to 1 at a time.

Also getting that Special Week card is really not hard, it's just too tight to get all the free copies right now which uncaps the max level of the card.
The ACTUAL important meta card is going to be Kitasan Black in a few weeks, it's actually more worthy to enter the game right now so you can get the resources to splurge on that banner.