Jigglypuff Found in Safari zone (I think)
You don't. You have to trade an eevee to Pokemon Ruby to use one in the game.
clafairy
Use Dive.
Skitty evolves into Delcatty through the use of a Moon Stone in Pokemon Ruby and Sapphire.
Most Water Pokemon can learn surf in Ruby, like tentacool or wingull.
Combined with the sapphire the ruby and sapphire will allow you to trade with ruby and sapphire and emerald.
give it to your pokemon, it will raise its Contest condition.
I always use Roselia, or cacturn.
Pokemon ruby's version IS Pokemon ruby.
use the itemfinder
use a moonstone
EVEE