How do you get Marill to appear in Mt. Mortar?

Question

I've been searching for hours now and not a single one has popped up.

Comments

Heartgold its in the tags

Answer 1

You need to have Professor Oak says that Marill appear in Mt. Mortar. Then, Surf on the water. Walking in the cave works too. It is VERY rare.

Comments

Man that sucks thanks mew