Unfortunately the only real easy way to catch rayquaza is to use your master ball. if you really want to save it for Latias/Latios (Which you shouldn't because rayquaza is 10x better) is to paralyze him and then use the best ball you have in your inventory, but first you must get him down to low red in hp.
You cannot get Rayquaza in Pokemon FireRed. Rayquaza is a Pokemon only available in Pokemon Ruby, Sapphire, and Emerald through normal game play and Pokemon Diamond, Pearl, and Platinum by hacking or trading. It is not available throught trade, hacking, or normal game play in Pokemon Fire Red. Rayquaza is a Pokemon of the Hoenn Region (Pokemon Ruby, Sapphire, and Emerald), not the Johto and Kanto regions (Pokemon FireRed and LeafGreen).
Rayquaza cannot be caught in Pokemon Diamond or Pearl. You'll have to migrate it from Pokemon Sapphire, Ruby, or Emerald to the Pal Park or trade for it.
You can't catch it in XD. Try catching it in Pokemon Emerald.
Catch Kyogre, then trade a Groudon from Soulsilver. Take both of them to Professor Oak, and he'll give you another orb. Rayquaza will be at the same tower as the two others.
You'll need to either:
You can't catch almost any of the legendaries from the previous games, unless you use a cheat code. The only way to get a Rayquaza otherwise is to trade via wireless with a friend.
you trade rayquaza from Pokemon emerald(or other games depending which you have your rayquaza on) to fire red to get rayquaza on fire red, you can only do this after helping celio after cinnibar island gym
Rayquaza cannot be caught in Pokémon FireRed and LeafGreen. Trading it over from Pokémon Emerald is required. You must first obtain the National Pokédex from Professor Birch after beating the Elite Four, though.
Rayquaza isn't in Indigo. Rayquaza is ony in Pokemon Ruby, Sapphire, and Emerald.
You can't find rayquaza in pokemon platinum.
any Pokemon has the potentional to beat rayquaza theres no 1 Pokemon that can beat rayquaza in battle although if you want his weaknesses his weaknesses are dragon and ice
You can't get Rayquaza in Firered.
There is no way of getting it.
Rayquaza.
You can only get Rayquaza in Pokemon Ruby, Sapphire, and Emerald. If you want to get a Rayquaza in Pokemon Leafgreen or Firered, you will have to get a second Game Boy Advance or SP with a link cable to trade Rayquaza into your firered or leafgreen.
You must trade from Ruby, Sapphire or Emerald.
you trade rayquaza from Pokemon emerald(or other games depending which you have your rayquaza on) to fire red to get rayquaza on fire red, you can only do this after helping celio after cinnibar island gym
Rayquaza isn't in Fire Red/Leaf Green.
Groudon, Kyogre from sapphire, Rayquaza, Mewtwo from firered or leafgreen, Zapdos and Articuno again from firered and leafgreen.
Groudon, Kyogre, Rayquaza, Zapdos, Articuno, Mewtwo.
Rayquaza cannot be caught in Pokémon FireRed and LeafGreen. Trading it over from Pokémon Emerald is required. You must first obtain the National Pokédex from Professor Birch after beating the Elite Four, though.
i think its charizard (if choose) kyogre,groundon or rayquaza and dialga or palkia from dimond or pearl
You trade from Pokémon Emerald to Pokémon FireRed but to trade between these games, you must have done everything on all the Islands on FireRed which includes getting the Sapphire and Ruby stones, beating the Pokémon League and getting the National Pokédex on Pokémon Emerald.