You have to give the move tutor in Blackthorn city a heart scale, and he will make piloswine remember it. The next time he levels, he will evolve into mamoswine.
krabby
Yes.
Mostly any pokemon.
no
No.
aeroblast
if you have the machine click on it and if there is the word ABLE on it, it can learn it
Level 41
lugia and fregulater and charmander
Level 22
All of them
bellsprouts can learn it or pikachu (EDIT)** my togepi knows it