Help weird post game quest I can't find ANY information about?

Question

I was playing omega ruby and I was in mauville city when I saw the gym leader standing by that tower in the center that seems to have the same concept as the prism tower in X and Y. When I talked to him he said something about how it's shining which means something bad is happening. He said to meet him somewhere. I can't remember where he wanted me to go which is why I'm asking this (not shure but I THINK he said something about his house being on the second floor of some hotel).

Answer 1

You have unlocked the New Mauville Sidequest! New Mauville is a lone building located on the waterbed of northern Route 110 (i.e. just below Mauville City). You are meant to go to the Mauville Hills, which is accessible via the previously inaccessible elevators scattered around Mauville City, and you're to find Wattson's apartment. Once you've talked to Wattson, you should be able to surf over to New Mauville and fix up whatever the issue is over there.

This video is a visual demonstration on how to do the sidequest: https://www.youtube.com/watch?v=MgKQ3XG3AX4

Hope I helped. :)

Answer 2

Yes. He wanted you to go in his room of the second floor hotel. I found it pretty hard to find it but one of the guards of the room that is NOT it will give you a Lopunnite. I wish you luck finding it.

Source: Experience (im stuck on the delta episode)

Answer 3

The Mauville City Gym Leader, Wattson, wants you to meet him at his apartment in Mauville Hills. (The second floor of Mauville City.) Wattson's apartment is apartment 13.

Source