after you get the national dex you can give it to a seadra and trade it to get a kingdra.
On six island go to ruin valley but don't go to dotted hole instead use surf and go south you will find an item its a dragon scale. Now give the dragon scale to hold to a seadra then trade it to a friend then take it back and it will be kingdra.
not in fire red
At celadon game cormer
you dont
Seadra to evolve it into a Kingdra.
It only evolves If you trade it with a dragon scale
Bagon carry it on them. (5% chance though)
you use a dragon scale and trade Nobe
the 7 island Pokemon tower owner may give you it.
give sedra a dragon scale and then trade it . it will be kindra when you trade it
Go to six island and go south use surf and go down some more until you reach a little platform with an item this is the dragon scale.
The Dragon Scale is in the trainer tower at the top of island 7. you must beat the trainer tower on doubles or beat it twice. Also there is one located near in ruin valley on six island need surf to get it.
On six island go to ruin valley but don't go to dotted hole instead use surf and go south you will find an item its a dragon scale. Now give the dragon scale to hold to a seadra then trade it to a friend then take it back and it will be kingdra.
You can find TM Dragon Claw on Victory Road in Pokemon FireRed (Kanto).
you have to catch a dragon Pokemon holding a dragon scale
You can get King's Rock, Metal Coat, Upgrade, and Dragon Scale by beating the Pokemon tower on one of the islands ( not sure which one, to lazy to look).
The dragon scale evoles seadra to kingra.When you trade seadra holding a dragon scale it will evolve to a kindra!