Add joim as an alias of join

In recognition of your outstanding accomplishments in the field of
Pokémon sciences, we hereby award you the highest of honors; a
commemorative alias.
Merge pull request #1303 from ScottehMax/patch-1

Add joim as an alias of join
Remove unnecessary checks for sound immunity
As of ecbc9bfd62, no effect provides an "immunity" to sound.
Correct Cheek Pouch mechanics

Didn't know this was still set to 25%...