Attack of the Rolls (as well as the other hacks some of us uploaded) use an older version of SOR2: Syndicate Wars as a base. Pancakes 2 should come with a guide for Syndicate Wars, so you would do Open ROM with Guide.

I already know that, since I use Pancake since October, but I want to know, which Rolls (Garcia, Donovan) are all thhe same?

Hence the name "Attack of the Rolls", all the character slots use Roll sprites.

So wait: I have to replace ALL enemies like in regular Syndicate wars?

Yes. Some enemies seem to be incompatible with the import feature.

Interesting. One more question: How do I change the color palettes back to default?

Do you have Palettes of Rage? Syndicate Wars' default palette is located at address B964.

I do have Palettes of Rage, but I have no Idea how to acess SW palettes via PoR, because everytime I do that it looks all so black.

Because things are in different addresses.

So, how do I change the Color Palette's in SW? Can you explain it in steps please?

I'll just link this guide to all the SW palettes I know of: https://pastebin.com/R5H7NscG

Many thanks.
One question though: There's another playable Roll on the right, is this supposed to be Axel?

Axel's char ID is right after Max, so yes.

Ah, ok. But what happened to the sound? It's so hight pitched. Can I lower it?

We had a little bit of fun messing with the sound driver in the game.