Akuma and Gouken are two fun characters to play but if you want to play them prepare to do a lot of work. The Capcom
blog has details on how to unlock both and let me say that it's definitely not a piece of cake to do this. Can't say Capcom doesn't make it a little tough for you but hey if you really want to play those two I'm sure you are going to spend a lot of time going after them no matter how hard iti is.
