Rayqyasa Groudon Kyrogye Latios/latias regirock regice regsteel
only latios and latias
beat the Pokemon league in fire fed and emerald then trade them and if you want duplacat them.(duplacating only in emerald)
Deoxys is a legendary Pokemon and cannot breed in Pokemon Emerald. This Pokemon can only be obtained through trade and special Live Nintendo events.
You can only get groudon if you migrated it through the pal park from Ruby or Emerald.
This legendary Pokemon can only be acquired on Ruby Version through trade from Sapphire Version or Emerald Version.
Groudon is a Ground type legendary Pokemon and the mascot of Pokemon Ruby. It can only be found in Pokemon Ruby, Pokemon Emerald, and in Pokemon SoulSilver is the player obtains a Red Orb.
The legendary dogs Raikou, Entei and Suicune does not exist in Pokemon Emerald, the only way to get them is to trade them from Firered or Leafgreen, but also there you can only get one of them, it changes of what starter you choose, Bulbasaur-Entei, Charmander-Suicune, Squirtle-Raikou, and they're relised after you complete the Pokemon leaguage. Any other Pokemon questions, check out Psypokes.com or Serebii.net
The only one i really know is ditto.
the only legendary Pokemon in ruby sapphire and emerald is regirock regice regsteel,rayquaza,groundon[ruby],kygore[sapphire]emerald can get rayquaza groundon and kygore and latios for ruby latias for sapphire and i don't no about emerald in emerald u can also get ho-oh and lugia
In emerald only here's all the Pokemon you can get: Mew (event only) Latios and Latias, Groudon, Kyogre, Rayquaza, Deoxys (event only) and lugia and ho-oh (event or get one from Pokemon colosseum and Pokemon xd gale of darkness), also if you trade the legendary birds from leafgreen and firered to emerald you can have them and you can have mewtwo also celebi (event only) and jirachi (Pokemon colosseum pre ordered special disc) also the legendary dogs raikou, suicune, entei from firered and leafgreen and last but not least the regis regirock regice and registeel.
If You have The ROM i am pretty sure that not only the three Legendary Cats, but Zapdos Moltres And Articuno are in there too Suicune=Cheetah Entei=Lion Raikou=Tiger
yes if you use a ditto and put they into the same day care ^REALLY?!? to my knowledge all breeding of legendary Pokemon that has ever been attempted failed. The only legendary that can breed is Manaphy. (he's a sinnoh legendary)