Suggestions:
1. When you go to fortree, go left,and you see the long river? if you surf down the river for a while, youl get to a secret base. its in a tree,
2. The ones near the left side of fortree that require the Acro bike. I heard that match bakes are more popular, so if he uses match bikes, he wont find it for a while.
3. Any sea route one thats on a amall island. Prefarably not with firsherman, becasue your frind might go there to batle them one day, and find the base.
3. the one that when you go north from rustborow, you have to surf a while, then you get to that island. then use one of the ones that require the match bike to get up to.
4. when you go through the tunnel in verdenturf, you can get to a small place. this is where you get the blackglesses. one of them there will work
5. when you go east from fortree, after following the path for a while, youll find a placee where youll have to cut to get there. there are are also a few berry spots there, sso youll know when you find it.
6. anywhere on route 123, under mount pyre.
7.Nort of mout pyre, and below the safari zone. there is a place where you have to cut a few times to get there.
Note: the closer to one, the more reccomended.
They are still all HIGHLY recomended. 7 is just the least out of those 7.
Those are my suggestions. tell your friend: happy hunting!