well you can get groudon with an ultraball so dont use your masterball and there is also rayquaoza or however you spell it the green dragon pokemon. then there is registeel and two other regi something
if you want to cheat to get all legendary Pokemon on ruby you have to play on the computer
No.
you can't get the black flute in leaf green but you can in Pokemon ruby, sapphire and emerald then trade it to leaf green.
Have a ruby or another sapphire trade you a legendary!
Groudon and Rayquaza
There are 6.
Ground
The Legendary Pokemon in Ruby are Kyogre, Groudon, Rayquaza, Deoxys, Jirachi, Latios, Latias, Regice, Regirock, and Registeel.
You cannot get the Legendary Dogs (or Beasts such as Raikou, Suicune and Entei) in Ruby without either trading for them or cheating for them because they are not available in the wild in Ruby in any way, shape or form. But you can catch it in Pokemon Ruby Destiny-Reign of Legends. But in the original Ruby or Sapphire you can't get it.
It is in the wild, anywhere. Whenever you change location (go into houses, etc) it will change place. You need to 'unlock' it before you can get it though.
groundon, latios, rayquaza and the three regis.
Groudon the big red one