I only know Regi rock,regi ice,regi stell and raquaza
if you want to cheat to get all legendary Pokemon on ruby you have to play on the computer
There are 6.
The Legendary Pokemon in Ruby are Kyogre, Groudon, Rayquaza, Deoxys, Jirachi, Latios, Latias, Regice, Regirock, and Registeel.
No.
Ground
unusual u will get legendary Pokemon
groudon but in a updated version.
you can find the legendary Pokemon regirock
Have a ruby or another sapphire trade you a legendary!
If you flee from one of the Regis in Pokemon Ruby it will disappear from the game. This is the same for all Legendary Pokemon in all Pokemon games. The Roaming Legendary Pokemon are an exception as they can flee from battle without disappearing.
You battle it and you choose whether to catch it or not.
It's a cave, there's is a legendary Pokemon in it.