There's already a DLC thread on here.

Also just because a character has a darker color palatte and possibly some different moves doesn't mean they're Evil.

For instnace there is no Evil Sakura, there's Sunburnt Sakura, which was translated as Dark Sakura in the US version, but she doesn't use the Dark Hadou like Evil Ryu does.

Actually, in Marvel Vs Capcom 2, Dark Sakura does indeed use the Dark Hadou, I've done this plenty of times myself. Also her hadoukens/fireballs shoot straight like Ryu's as opposed to skyward. Plus she teleports like Akuma. I still own Marvel Vs Capcom 2 and all this is very much there. 

As for Evil Zangief and Evil Chun-Li, they don't exist. There's Mecha Zangief and Shadow Lady, but neither character is Evil they're just "for fun" chars.

And btw let me point at that all these variations of characters that you want are basically the exact same character just with a different coloring, ie does Evil Ryu, Dark Sakura, or Shin Akuma act any differently from their normal counterparts? No, they act exactly the same and don't really have any different moves meaning they could just include these darker color palattes as alternate color palattes in SFIV without having to make them seperate characters.