Playing through the battle system right now, and seems like fun strategies could evolve
Super Starter: V for Victory introduces you to all the basic types of cards and also includes cards like the Gagaga monsters to help you get comfortable with Xyz Summoning
One-Hit Kill: Gustav Max was a key card in an OTK, based on looping its effect continually with a combo of Elemental Hero Electrum and Chain Material
DYNAMIC GAME - Immerse yourself in exciting battles with new Pokmon, trainers and special energy cards introduced in this expansion, promising depth and excitement for your matches
The black triangle 1st edition error packs scarcity hints that there had been a very low print volume, but no reliable information has been brought forward of their exact print duration
There was a thread a few months back for the Pok-Emotions game with a focus on Sleepy linked here which would likely give you a starting point, but I would imagine it is not all inclusive to every card with a sleeping Pokemon