This is one of those things where the answer is no.
Fanart on it's own is OK and a great way to build an audience, but once you sell it, then it can be taken down pretty quickly with a DMCA, it can happen even if you're not selling it (like I forget who it was, but there was this guy on youtube who once wore a Toad costume to talk about a video game--got DMCA'd) I mean I've been DMCA'd before and it was mostly over showing characters (even characters that were very exagerated or in an AU) or using advertising tags that involve their property. Stuff that is fan-adjacent, there's a fine line there and you can argue that, and I've sold on that fine line...but again this is basically a risk. It's a risk.
People who sell fanart a lot, probably have licensing to do it. Which is something you can obtain, but it costs a lot of money so only do it if that is your whole business plan.
So you sell it as a risk when you sell it. People do it who aren't licensed--and art alleys have gotten in trouble for this since the culture has this expectation to sell fanart unlicensed--which is it's whole own deal and it depends on the art alley if they got permission to sell fanart or if they are just turning the other way and choosing to ignore the copyright violation. But no one can stop you from uploading it, but it may not stay up there long. You probably won't get sued, but you absolutely can, you can get our account shut down from enough violations, and so it isn't recommended to throw pikachu in there--I personally would stay away from Nintendo characters right now since Nintendo has recently stepped up their DMCA takedown game--just put in original art instead.
