I haven't played for a while but you can find some if you know the move dive. I can't remember where exactly but I don't think it matters, just dive anywhere. But it's a rare pokemon so it might take a while.
You find relicanth underwater near sootopolis city.
No only in ruby and sapphire and emerald.
You can't catch Relicanth. You have to trade from Ruby, Emerald, Sapphire or any other game that has him captured.
Sootopalis City
A relicanth cannot be caught in leafgreen but you can catch one in ruby, sapphire, and emerald.
no you do not have to catch a relicanth to get a rayquaza
near sootopolist
sorry NO. but you have to dive
They're a rare Pokemon you can find underwater just outside of Sootopolis. Other than in Ruby, Sapphire and Emerald, you cannot obtain them.
You can catch it when you use dive.
there is a slight chance of a Relicanth holding one when you catch it wild. you can also find the underwater and on beaches in pokeballs on route126
Relicanth appears in Pokemon Ruby, Sapphire, Emerald, Diamond, Pearl, Platinum, Heartgold, and Soulsilver. In Ruby/Sapphire/Emerald you can catch it pretty much anywhere in the Underwater, using Dive in the sea. In Diamond/Pearl/Platinum, you can catch it by using a Super Rod on Route 226. And in HeartGold/SoulSilver, you catch it on Route 12.