Only if you have aurora ticket yes.
Mewtwo, Deoxys, Ho-oh, Lugia, and Mew(I think).
There are Eight. They are: Zapdos Moltres Articuno Entei Suicune Raikou Mewtwo Deoxys
To get Deoxys, you need the Aurora Ticket from a Nintendo Event. To get Latias, they are in the wild after you beat the Elite Four. To get Mewtwo, you need to trade from LeafGreen or FireRed.
Mewtwo, articuno, zapdos, moltres, raikou, suicune, entei, deoxys (event only), ho-oh and lugia (event only).
you can get deoxys at birth island
All the legendaries that are in firered are: Moltres, Articuno, Zapdos, Mewtwo, Lugia (event only), Ho-oh (event only), Raikou/Suicune/Entei (depends on starter pokemon), Deoxys (event only).
There is no deoxys
you get 60 Pokemon beat the elite 4 and go to the cerulean cave mewtwo is somewhere in there
the rare Pokemon in fire red are the legendary Pokemon and there is only one of each. they are Zapdos, Moltres, Articuno, Mewtwo, Lugia, Ho-Oh and Deoxys
You can find Mewtwo in the Cerulean Cave.
Moltres, Articuno, Zapdos, Mewtwo, Raikou/Suicune/Entei, Ho-oh (event only), Lugia (event only), Deoxys (event only).
Deoxys is a legendary Pokemon which has various different forms. To find one in FireRed version, you need to have an Aurora Ticket.