A format is a set of rules about which cards you're allowed to put in your deck. Every format uses the same basic gameplay. What changes is the card pool and a few deck-building restrictions.
The big four at a glance
| Format | Card pool | Special deck rules | Best for |
|---|---|---|---|
| Standard | Recent sets (by regulation mark) | 4-copy limit, 1 ACE SPEC, 1 Radiant | Tournaments, TCG Live ranked |
| Expanded | Black & White series onward | Ban list, 4-copy limit | Combo lovers, veteran collections |
| Gym Leader Challenge | Expanded pool | Singleton, one type, no Rule Box | Budget play, creative deckbuilding |
| Casual | Whatever you agree on | House rules | Family, friends, theme decks |
Which should I start with?
If you're brand new, start with theme decks or Standard. Standard is what most stores run, and the card pool is smaller, so there are fewer cards to learn. If you're on a budget or love deckbuilding puzzles, GLC is a fantastic second format: you only ever need one copy of each card.
Rotation in one paragraph
Each year, the oldest regulation marks leave Standard. Those cards don't disappear: they're still legal in Expanded, GLC and casual play. Rotation just keeps Standard fresh and gives new players an easier way in.
Tip: Before building a Standard deck, check the official Pokémon website for the regulation marks that are currently legal.