Where is the move relearner's key?

[Ban Suicune]

I know she's chillin outside her house but I don't know where this careless woman's key is and i require her services ( ͡° ͜ʖ ͡°).

Sorry if I broke any rules on posting and thanks in advance for the help. Feel free to berate me if this isn't the place for this post, I'm #new.

[Timber Dragon]

It's in the Underground Railnet in the place with the train track puzzle. Somewhere near the end of the first hall is a darker crack in the wall. Use Rock Smash and you'll enter a small room with the key.

[phoney]

like the one where u can access chrysolia forest from?