http://sakuga.yshi.org/ one of the best reference sites imo. explosions, running, fighting, vfx, p much anything u could think of
imo dont learn animation from other pixel artists; learn animation principles from people who've been doing it better for decades. animators survival kit is an oft-recommended book, start there.
tho to really get good at animation you need to have a firm understanding of anatomy (which is why most pixel artists hit a skill ceiling v quickly). without that (and other art fundamentals), you will flounder forever.
basically, study from traditional art, and apply those principles towards pixel art, instead of focusing purely on pixel art. otherwise you're going to pidgeonhole yourself! it will take Years of hard fucking work, but if you're serious about getting good (and you have to be serious), it's the only way to make real progress.
