You have to have all of the Gym Badges for him to move.
You have to get all eight gym badges
You finish the Pokemon league and get the national pokedex You finish the Pokemon league and get the national pokedex
go to the Pokemon league and get a job
catch dialga`then that fat guy will move
you beat the pokemon league and if youre talking about the one on victory road you have to get the national pokedex
you have to beat all the gyms before the harthom one
He is in Pastoria in the house with the fat guy standing outside! REMEMBER you must have a heart scale in order to get a move!
Marley is in the part where the guy is blocking the door. You have to get the national dex (see all sinnoh dex Pokemon, then go to rowan) and beat the Pokemon league.
happiny
if u had an ar you could use the walk anywhere cheat to go around him
go to lighthouse (top) talk to gym leader
Define 'gray guy', there are lots of special characters in Diamond