I'm not sure about sprite sheets and such, but you are unloading your own work, which is something of a "no-no." You might want to review the uploading guidelines at your convenience.
I personally don't care if the artist is uploading their own work; there's issues with it, but that's not usually the reason the art isn't approved. In principle, there's also nothing wrong with sprite sheets. The problem is that the quality standard for pixel art here on danbooru does not really allow for such low resolution sprites. post #483697 and post #760518 are the only true spritesheets I know of on danbooru, and you'll note a clear quality difference compared to these.
There's also the matter of these type of sprite sheets being essentially nothing more than edits of official sprite sheets ripped from the games.
Just to clarify, lowres by itself doesn't disqualify things from being good enough. Neither does being a sprite sheet or pixel_art. But I agree these sheets simply don't cut it, being straight rips from the game and not much more.
Also, as a note, flagging posts because they are self-uploads or whatever other external factors is not the right thing to do. We discourage self-uploads, but things that already got uploaded should be judged based on their own merits and nothing else.