Yes his house is a small ways west from mossdeep city.
Near mossdeep ciry
Trade a green shard to the hunter to get a leaf stone.
That can be found underwater near the hunter's house west of mossdeep city.
I think there are an Unlimited number, because if you manage to get a green shard from a wild pokemon, you can trade it with the shard hunter for a leaf stone. (He has an unlimited number of them, as long as you have a green shard to give him.)
find one in the firey path or trade 1 red shard for one at the hunter's house
you can find it on route 124 I've had a vulpix and to make it evolve i had find the red shard and i had to give it to hunter in mossdep city to get the fire stone
from trading a blue shard with hunter on island near mossdeep. There is one you can find in the abandoned ship.
You can trade a Blue Shard at Hunter's House for a Water Stone.You can also get one in the Abandoned Ship.
Trade a red shard with the hunter to get a fire stone.
You first need a yellow shard these can be found using Dive near the Hunter's house, Second give the yellow shard to the hunter he will trade you a thunder stone for the shard. Another way to get a thunder stone is by trading a Pokemon from firered or leafgreen that is holding one to ruby, sapphire or emerald.
Underwater
you can't get them in sapphire and emerald. You have to trade the green shard to the treasure hunter dude near Mossdeep city to get a leaf stone. Green shard can be found near that treasure hunter dude house, you may have to dive up and down many time to reach it, you can also find the red, yellow shard this way. Good luck