Okay, first thing first, yes, we do ban for art theft. That is something we take very seriously here, and people have been permanently banned from it before. Sarcastic Dragonair, I have reason to believe those aren't yours. The watermarks are all very different, the styles of art are very different, and like someone pointed out earlier, they link to different accounts on DeviantArt. If they were yours, I would have noticed some similarity between the pictures, but I see nothing like that. However, rather than raising hell about this and running the possible risk of banning someone innocent, I'm giving you a chance to prove you did to them under terms I think are quite fair.
I want you to make a picture of a Pikachu riding a Latias over a beach with a sunset in the background and a few stars in the sky, and yep, I want it to look just as good
(if not better) as those pictures. If you really made those pictures, then that should be no problem, right?
You've got 48 hours, which is plenty of time. I have seen people do stuff like this in under 2 hours, so this is perfectly fair. If you don't do it, sorry, I'd have to consider that you didn't really do those pictures and flag it as art theft. And yes, you will get a permanent ban from it because we don't tolerate that here.