How do you catch latias in Pokemon Fire Red?

First, you must have to be strong enough to beat and catch it(and you must have the pokedex). Next, go to Pallet Town and talk to your mum. Then, talk to Gary's sister Daisy(i dunno her name was right or not). After that, talk to prof.oak. Finnaly, go to the last Pokemon of prof.oak and press A Button and Latias will appear!(sometimes it works and sometimes not)

Latias isn't wild in firered (latias is a HOENN Pokemon). You have to trade it from emerald or sapphire once you complete the tasks for CELIO at Seven Island.