Self explanatory
theres quite alot but the only few I can remember are chatot,buizel,lucario,zorua,zoroark and ho-oh
On my account, you could play enough of the current version to see a Pokemon before it appears in the show, this accounts for all current Pokemon. The only Pokemon that I could remember seeing before I saw it in the game(s) was Spearow of the very first episode of Pokemon, excluding Pikachu.