Emerald, because it's just as if you've taken Ruby and Sapphire and put it into one game to make Emerald; though I think it should be called Pokémon Amethyst and Rayquaza was purple, because Red and Blue mix to make purple! Just a bit of creative thinking, but yes. I would go with Emerald as you can get both Groudon and Kyogre, battle both team aqua and team magma. Plus the biggest bonus of Battle Tower and getting a Sudowoodo and Smeargle at Battle Tower area! I think it's called battle tower, or battle frontier? Haven't played it in a while personally.