How do you get Lapras in Pokemon FireRed?

You can find in ICEFALL CAVE (need waterfall to reach it, 1% chance of finding one or A guy gives it to you in silph co (lvl 25) *Edit* You can also trade one from Pokemon XD: Gale of Darkness after you purify it and beat story mode.- matty502
Lapras can be found in the water in Icefall Cave on Four Island. The islands can only be reached after defeating the Elite Four, and lapras is very rare, so be sure not to kill one should you find it
You receive Lapras from a Silph Co. employee as a gift while making your way through the Silph Co. building.
Lapras can be found at Icefall Cave Floor 1, or you can get one for free after beating your rival at Silph Co.