MinMin has 3 different types of arms: Ramram, Megawatt, and Dragon. Ramram is fast, agile, and does the least amount of damage and is a great tool for edgeguarding. Megawatt is big, bulky, slow, and meant to kill. Lastly, Dragon is somewhere in between that also shoots beams and is another great move to edgeguard.
MinMin's neutral b controls her right arm and is just a mear punch. The right arm is only controlled by the B button and the left arm is controlled only by the A button.
The side b is just the direction. It can inputted in both the A and B buttons and can allow you to punch in both directions at the same time.
Her up b allows her to snap to the ledge when in midair. While on the ground it acts like a huge jump allowing you to reach higher places than before.
Her down b allows her to switch between the three types of arms for her right arm only. Her left arm is constantly at the dragon arm and cannot be changed.