Play as vanilla Sagat, for instance
In a move that is sure to be divisive among the fighting game community, Capcom has revealed a new feature in Ultra Street Fighter IV -- the ability to select "past" incarnations of characters. For instance, if you were playing the newest version of the game, as a general rule, you can only play as the newest version of that character.
But in Ultra, you can choose from Vanilla SFIV, Super SFIV, Super SFIV AE, Super SFIV AE 2014, and Ultra SFIV versions. This is a pretty massive change, as it forces players to counter or master every single type of character. It'll also allow some pretty crazy tournament level matches, as pros can "bring back" their favorites that have won for them in the past.
Ultra Street Fighter IV Edition Select [Capcom Unity]