You would have to get a groudon from someone else if you wanted one before you beat the game.
no
nope, only ruby, kygore is the ledgandary of the game, and when i say that, its the ledgandary Pokemon on the cover.
if you did, congradulations! you beat the whole game!
you are able to get groudon later in the game and the flying red and blue dragon, but you have to beat the game
Of course find groudon in terra cave save before attempting to capture it then when you see it if its not a brownish color keep resetting the game until its shiny.
first you have to beat red after you beat the game and get rock climb then go to red i suggest level 70's but i did it with level 70 and lower, next get the kanto starter then go to mr Pokemon you get the red orb then you can get groudon
The only way is if you saved your game before attempting to capture it and if you failed you can reset the game and try again other than that its not possible to retry catching groudon you can however take a groudon from emerald if you failed to catch it or another ruby game. So, no.
groudon appears in soul silver.
Well a bunch of things unlock you could get groudon or you could just start a new game i can't beat red anyway lol but that's a pretty good thing to do get groudon is my answer hope you can get to him!
For Raquazza, you have to complete the main game and then go to sky tower. It's the same for Groudon. For Kyogre, I don't really know. I only beat the game and got legendaries.
Ruby and Emerald.