I'm looking for a guide on 2D animation. I'm very new to it. Specifically what I want is to find the minimum amount of sprites needed in an animation cycle to simulate fluid/semi-fluid movement.

ex) Maybe a highly detailed walk cycle has 10 unique sprites in its spritesheet. But a minimum acceptable walk cycle that tricks the eye well enough can be done with only 5 unique sprites.

Now I want to apply this knowledge to other visual animations such as a wizard's cape flowing in the wind, or a flaming fireball (as opposed to just a static fireball image that translates across the screen).

Could someone recommend a guide out there that will put me on the right track to attaining the skills needed to do some basic 2d animations.

Don't have a specific guide for that for you but what I've noticed doing 2D animations is only drawing every 2 frames of the "full" animation which makes the animation fluid enough, at least for me

example a door what I drew, skipping every second frame from a "full animation"