In Pokemon Emerald, how to go to Sevii Island? And what can i do at altering cave?

Question

i'm so confused, tell me please!

Answer 1

There's no sevii islands in Pokemon Emerald. They only exist in Fire Red and Leaf Green. The altering cave is situated on route 3 and after the Elite 4. You can find several rare jhoto pokemon here. Here's a list of them:

http://www.serebii.net/emerald/altering.shtml