You need to learn the HM strength.
Rock Climb is not a move in the game. It wasn't a move until Diamond/Pearl/Platinum, which came out after FireRed.
Rock Slide is taught by a move tutor in Rock Tunnel.
use the move Flash (TM70)
Either by using the HM Strength or by using the HM Rock Smash
You need the mystic ticket to get to navel rock on firered.
Most rock type Pokemon learn this move like Aerodactyl.
Use any Water type move, Ice type move, Rock type move, Steel type move or Electric type move.
There is one King's Rock to be found in Pokemon FireRed in Sevault Canyon. They can also sometimes be found on wild Pokemon like Poliwhirl.
You can catch a Ho-Oh at Navel Rock in Pokemon FireRed.
either naval rock or just not in firered
Use the pokeflute.
RFDHDF