Pokémon Ruby and Sapphire/New features

Ruby and Sapphire

 * 135 new pokemon introduced
 * new region called Hoenn
 * 2 on 2 battling
 * pokéblocks
 * Berry Blending
 * Team Aqua and Magma
 * Pokénav
 * New TMs and HMs
 * New pokémon moves
 * Introduced Pokémon abilities
 * GBA graphics
 * Origin Cave

Emerald

 * Battle Frontier
 * Expanded Safari Zone
 * New attack called Volt Tackle
 * Changes in pokémon abilities
 * Marine cave
 * Terra cave
 * Trainer Hill
 * Johto Starters
 * Different Event Pokémon
 * ability to refight gyms
 * New Characters
 * Different ways to get the Regis
 * Battle tents in place of Pokémon Contest Halls
 * Pokémon Contest ranks all held in Lilycove City