Regis, Regigigas, Latias, Latios, Rayquazza, and I'm not exactly sure you can catch Kyogre or Groudon, but I know for sure the first ones I mentioned
all the legendaries and how to get them here http://www.psypokes.com/emerald/legendaries.php
Use Gameshark.
beat the Pokemon league in fire fed and emerald then trade them and if you want duplacat them.(duplacating only in emerald)
You have to trade it from FireRed or LeafGreen
all i know is how to get the regis and latios or latias.
Rayquaza if you want the details go to serebi net and type in rayquaza
No,but you can migrate your legends from firered leafgreen emerald ruby or sapphire
you canmigrate from firered, leafgreen, ruby, saphier emerald ur welcom :) :(
Nowhere. You can't. You have to trade them from the FireRed and LeafGreen versions.
1 hack 2 master ball cheat 3 use the have every legendary code
Yes and no. You do need all three starters, and you need every legendary except for Deoxys, Celebi, and Jirachi.
No, because Rayquaza can't breed. None of the legendary Pokemon in the game can breed at all.