You can either evolve a tentacool found in the water when Surfing, or, if you're lucky, you'll find an already evolved tentacruel.
in route 111,114,120 it is common their
It is given to you by a fisherman on Dewford.
I think its the same place you find him in Ruby and Saphire
You don't.
you cant get regigigas on Pokemon emerald its to ew of a Pokemon
from boos and from mali
in a cave at the town after sootoplis
trade from leafgreen or firered
this is impossible!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
There was never any Pokemon events for emereald.
Cutter's House in Rustboro
Get it in the contest hall in slateport city.