Like usual, two versions of the same game are available. Omega Ruby and Alpha Sapphire are nearly identical; however, there are a few differences between the two that are larger than most alternate versions.
The biggest alteration between the two versions is the main antagonist team. In Pokemon Omega Ruby, Team Magma will be the primary team you encounter throughout Hoenn. In Pokemon Alpha Sapphire, Team Aqua will be the primary team you encounter throughout Hoenn.
Version Exclusive Pokemon
In addition to slight story changes, select Pokemon will only be available in one of the versions. These version exclusive Pokemon are usually made to promote trading between players. All players can trade over wi-fi between X, Y, Omega Ruby, and Alpha Sapphire immediately after obtaining the Pokedex and installing the Player Search System app on the PokeNav Plus.
Omega Ruby Exclusives | Alpha Sapphire Exclusives
Groudon | Kyogre
Latios | Latias
Mawile | Sableye
Seedot | Lotad
Nuzleaf | Lombre
Shiftry | Ludicolo
Solrock | Lunatone
Zangoose | Seviper
Ho-Oh (Mirage Spots) | Lugia (Mirage Spots)
Palkia (Mirage Spots) | Dialga (Mirage Spots)
Reshiram (Mirage Spots) | Zekrom (Mirage Spots)
Tornadus (Mirage Spots) | Thundurus (Mirage Spots)
Kabuto (Fossils) | Omanyte (Fossils)
Shieldon (Fossils) | Cranidos (Fossils)
Archen (Fossils) | Tirtouga (Fossils)
Skrelp (After Groudon) | Clauncher (After Kyogre)
Throh (After Groudon) | Sawk (After Kyogre)
Mega Stones will not be version exclusive, but the locations of a handful of Mega Stones will change depending on the version.