In Super Street Fighter 4: Arcade Edition for the PS3 and Xbox 360, you can fight Evil Ryu in arcade mode, similar to fighting Akuma or Gouken in previous versions but with different criteria.
In order to fight Evil Ryu in arcade mode, you need to meet the following criteria: Don’t lose any rounds, and get at least one Perfect Victory. When you get to Seth, beat him with a Super or Ultra Combo.
Once you complete all of these, Evil Ryu will come out to challenge you.