Suicune, Entei, and Raikou were first introduced in Generation II's Pokmon Gold and Silver, and all three are great Pokmon ex cards in Pokmon TCG Pocket
Two big things matter in real games
Even Kaiba has more of a presence in the anime since his manga counterpart goes into a coma, revives himself, and then isnt present during the final duel
Dogmeat helps you along in this endeavor by creating Junk tokens when any creature with an Aura or Equipment attached to it attacks
For example, in the Black and White games, only Pokemon indigenous to the Unova region were catchable, so in the first Black and White TCG expansion, only Unova Pokemon were included
Sardelis suggests the play pattern will often be "creating the quirkiest token you can and then copying it a whole bunch", so perhaps there'll be some unusual squirrel tokens within