What legendary Pokemon are on Pokemon FireRed?

FireRed has the same legendary poke'mon as LeafGreen. You can capture:-

Mewtwo in Cerulean Cave

Articuno in Seafoam Islands

Zapdos in the Power Plant

Moltres in Ember Island

Lugia in Navel Rock

Ho-oh in Navel Rock

Suicune roaming around Kanto if your starter is Charmander

Raikou roaming around Kanto if your starter is Squirtle

Entei roaming around Kanto if your starter is Baulbasaur

Jirachi roaming around Kanto