Which pair of games began Generation III of the Pokémon video game series?

Pokémon Ruby and Sapphire began Generation III of the Pokémon video game series.

The games were released for the Game Boy Advance and introduced the Hoenn region, a setting inspired by Kyushu and nearby areas of Japan. Hoenn added new species, characters, abilities, moves, and battle features to the series.

Ruby and Sapphire also marked a major technical transition. They could not directly connect with the original Game Boy games, so Pokémon from the first two generations could not initially be transferred into them through the older Link Cable system. The games instead established a new hardware generation and a new collection of Pokémon.

Pokémon Emerald later expanded the same generation with a different story emphasis and Rayquaza as its cover Legendary. FireRed and LeafGreen were also Generation III releases, but they were remakes of the original Kanto games rather than the pair that launched the generation.