there is no thing that i know of
all smergale. very ussless they are.
the artistan cave in Pokemon emerald is at the south of the battle frontier, it is also a place where you can catch some really strong smeargle.
its not under a boulder its smeargle and there everywhere in artisan cave.
u can buy them in the battle frontier exchange corner for 1bp or find them in artistic cave.
There is a sudowoodo to the right of the battle palace near it is some water you can surf on go down and into the cave this is artisan cave the only Pokemon that is found here is smeargle other then that you can't find any other Pokemon in the frontier.
In a battle or a cave
its a cave on the battle frontier island i think in emerald. you have to water a sudowwodo and it will attack you and you will battle it. then you can capture it watever. and you i think surf to a cave where only smeargles live. kinda boring other than capturing those two rare pokemon.
Smeargle.
It only contains Smeargles.
smergle is in there and also outside of it there is a soodowoodo
Surf South of palace. Water Sudowoodo wiggle tree.
Can catch Smeargle only. Goet a few items, but that's it.