>>51296608No one else will ever recommend XY (Gen 6, 3DS, 2013) because the story is awful and the battles are too easy for anyone who has played the games before, but there is a huge pokemon variety and all the forced handholding will explain many things to you. It has one of the largest regional pokedex (as opposed to the national pokedex upgrade that includes pokemon only available by transferring/trading from other games) and biomes to explore. Again, you're playing it for the monster and environment variety because the dialog and difficulty balance is bad, and don't use Mega Evolution unless you're about to lose because it overpowers most of the game. After you get your fill of X/Y try Omega Ruby / Alpha Sapphire. ORAS is a remake of Gen 3 (GBA, 2002) that uses the engine and mechanics of X/Y, has the remaining part of the regional pokedex, and was the first 3D game with an advertised accessible legendary dump after you beat the game. XYORAS make up Gen 6, the 3D of the games looks fantastic upscaled, and the handholding of the games returning players complain about it just enough to teach new players many things about the mainline games.
Or just play Emerald on x8 speed via emulator, join the first playthroughs who get their shit beat in by surprise rival fights, and miss many Gen 1 and Gen 2 pokemon the game lacks. Or Gameboy Gen 2 (not DS remake) if you like the artstyle. Or Yellow if you want to experience "the only real pokemon".
Try Gen 6 if you want a 3D game, or plan for Yellow -> Crystal -> Emerald -> Platinum > Black/White 1 -> Black/White 2 for a chronological variety of graphics, monsters, release years, mechanic upgrades, and a taste of many regions to join breaking /vp/ Rule 4 that should all total a playtime of a "full game". Gen 7 isn't a good first recommendation but try it later, and Gen 8 is a cash grab release relying on brand name and girls. Legends Arceus should be played after Platinum to understand the references.