Well from what I know for sure there are Rayquaza, Groudon, Kyogre,Latias, Latios and Deoxys. I also heard that there are Registeel, Regice, Regirock, Jirachi and some more but I cant remember them. Hope I helped!
its not an emerald its RAYQUAZA the main legendary Pokemon in Pokemon emerald.
rayquaza
The three legendary Pokemon in Pokemon emerald is Kyorge, Groundon and Rayquazer.
Groudon, Kyogre, and Rayquaza. Groudon is the fire legendary pokemon, Kyogre is the water legendary pokemon, and Rayquaza is the air legendary pokemon.
Raquaza (sorry if I mispeled that)
There are no breedable legendary Pokemon in Emerald. In Diamond/Pearl/Platinum Manaphy is breedable with a Ditto. However, the offspring will be a Phione.
legendary Pokemon cant breed
all the legendaries and how to get them here http://www.psypokes.com/emerald/legendaries.php
Rayquaza is the mascot for Pokemon emerald which will be stronger than Groudon and Kyogre
yes
No legendary Pokemon cannot be bred
groudon,kyogre,rayquaza