Some are balanced and intentional, while others allow some combos to be too deadly, not even allowing your opponent to make any plays before the duel is over
Expect to mulligan multiple times each game
PRO TIP: If buying from eBay, always ask for more images if their photos dont clearly show the card: Corners (they may have whitening) Back (check if the design is centered) Holographic under light (it may have scratches) Once youve judged the condition yourself, then visit Pokemon Price
After all, the more cards you can draw, the more spells you can cast, and the closer you can get to your deck's win condition
Cards that make duplicate, extra, or double the tokens abound here, so if you can build something to take advantage of that excess while surviving through the turns when your stuff is a bit durdly and slow, you will have a powerful deck that can bide its time and then pop off
I look forward to seeing how that shakes out