Capcom vs. SNK 2 EO, EO being an acronym for "Easy Operation" (named after a mode in the game), in a 2003 fighting game for the Nintendo GameCube and Xbox. It is the updated version of Capcom vs. SNK 2.
The game's storyline involves large numbers of fighters from around the world and across time coming together to battle for the title of World Champion in a series of 3-on-3 or 1-on-1 battles. During the events, two powerful fighters, Akuma and Rugal, fight each other, and one gains the power of the other, turning into either Shin Akuma or Ultimate Rugal, and battling the player's team or single character.
The game boasts a large lineup of characters from Capcom and SNK's fighting game franchises, mainly Street Fighter and The King of Fighters, and contains four console-exclusive bonus characters: Evil Ryu, Riot Iori, Shin Akuma (Shin Gouki in Japan), and Ultimate Rugal (God Rugal in Japan) powered-up versions of four regular characters. Shin Akuma and Ultimate Rugal are the boss fighters, and display tactics typical of bosses from SNK Playmore's fighting games.