i mostly just use KDE Kolourpaint (like MS Paint but for GNU/Linux and etc) for it since it's familiar enough and not a nightmare like Photoshop, GIMP, or Krita are. i just prefer how simple it is..
like, i can do some art with it, it's not looking like a doodle usually. but usually Kolourpaint is for shitposts like the modified camerupt sprite that i attached.
it's also great for me when i wanna just do little touchups to some things. like move a couple pixels away or pick a colour's HEX code or something.
if i myself make pixel art from scratch on it, i can make some G/S/C-esque sprites, but not radioactive colours. i did modify a sprite of the player-character from Platinum though, and i think they turned out well even tho i only used KP :P