you can find "Victory Road" just before the Pokemon League.
look on your map.
Makuhita: Cave in Dewford Town, Victory Road Hariyama: Evolve Makuhita, Victory Road Meditite: Victory Road Medicham: Evolve Meditite, Victory Road
In victory road you need strength to get to him You must also have gone to Milstraton Cave (indicated on the town map) and captured Cobalion
same as diamond/pearl
first if you were smart you would know to check your town map and find it your self and second its south of victory road and north of opelucid city
in twin leaf town
Go through Victory Road!
Go to victory road and travel to the right
the map locates it in johto and once you beat all 16 gyms (johto and kanto) the professor of pallet town will make arrangements for u to go in. IT IS AROUND VICTORY ROAD!!!
The easiest way is to print out a map off the internet
http://www.psypokes.com/platinum/walkthrough.php?part=10
here is a link to a website that shows you!http://www.psypokes.com/rs/victory.phpthis is a perfect map of victory road for Pokemon ruby/sapphire(it helped me A LOT!)