Hoenn. Secret bases. Double battles. Ruby & Sapphire dropped in 2003 and changed everything — a brand-new region with 135 new Pokémon, abilities and natures that added real depth, and the first-ever double battles. Groudon vs. Kyogre. Team Magma vs. Team Aqua. The generation that taught a whole playground what "version exclusive" meant — you needed a friend with the other cartridge to catch 'em all.
Secret bases let you decorate your own hideout in the overworld — mix records with a friend and their base appears in your game. Contests gave non-battlers something to master. And the Battle Tower tested if your team was actually good or just overleveled.
GBA SP running Ruby — Hoenn in your handsSecret base interior — your underground hideoutGameplay simulation — walking the tall grass