get it in a trade
You can't without cheating, trading, or migrating.
Rayquaza can only be found naturally in the Hoenn region, so the Sinnoh region (which is where these games take place) will not have Rayquaza. You must trade, cheat, or live without him.
Cheating
no
Cheating, hacking, or trading.
You can't find Rayquaza it in pokemon diamond, pearl, and platinum. You just migrate it in Pokemon Emerald, ruby and saphirer
Not without cheating. Ruby can get Groudon and Rayquaza, Saphire can get kygore and rayquaza, but only Emerald can get them all.
i like balls
You can catch a Rayquaza by migrating it from Pokemon Ruby, Sapphire, or Emerald to the Pal Park with 100% catch rate. But the only other ways are to trade for it or use a cheating device such as an Action Replay.
You can't unless you trade with some one who has it and got it from migrating or cheating with an AR.
u can't
You can't, unless you have Action Replay, but there is no way you can get it without cheating or migrating...