Latias is from the Hoenn reigon.
You can find Latias in Soulsilver throughout the Kanto region.
Latias can be found roaming the Hoenn region after the defeat of the Pokemon League. Latias's counterpart Latios can be found on the Southern Island.
She is usually roaming the Hoenn region, or she is on an island that needs a eon ticket.
latias is in the MOVE called Pokemon heroes
latias is in Pokemon ranger signs.
he comes up and tells you latios or latias has migrated from hoen region and is roming around the kanto region.
You can't get to the Hoenn region in HeartGold or SoulSilver. However, Latias can be caught in HeartGold, which is a legendary from Hoenn.
He will give you one of the three Hoenn starters, and will also notify you of Latios' (Or LATIAS) arrival to the region.
latias
the movie latios and latias come out on is in Pokemon heros the 5th movie
Of course you can get a Latias in Pokemon FireRed. However, Latias is not a naturally found Pokemon in the game - you must trade it from Sapphire version. Of course, you could use a cheating device to obtain a Latias, but other than that, you will have to trade for it.
in southern island there was latias and latios you will meet latias in Pokemon sapphire and latios in Pokemon ruby