He will go away after going to four island and going into icefall cave finding HM7 and using it to go find Lorelei and helping her beat some rockets.
Go to four island and go in icefall cave find HM7 then use it to go up the waterfall go to the ladder then defeat the rocket talk to lorelei then leave and go to six island go back to the cave and the guy will not be there use Cut to open the door.
4 island in icefall cave to reach lorelei you need to find HM7 inside icefall cave.
Go to four island and go into icefall cave in there find HM7 use it to go up the waterfall in the cave go to the ladder you will find team rocket and lorelei beat the rocket grunt they will leave then you should leave to six island head to dotted hole and the guy won't be there use Cut on the door to get inside.
Try making sure you've done these things: -Retrieved the Ruby from Mt. Ember on One Island and given it to Celio -Battled the Team Rocket members in Icefall Cave on Four Island and met up with Lorelei Then I think you should be able to get into Dotted Hole.
In icefall cave.
Go to four island and enter icefall cave HM7 is in there and its waterfall.
He will go away after going to four island and going into icefall cave finding HM7 and using it to go find Lorelei and helping her beat some rockets.
Go to four island and go in icefall cave find HM7 then use it to go up the waterfall go to the ladder beat the rocket talk to Lorelei then go back to six island the guy shouldn't be there anymore.
You must get to the sevii islands, go to four island, you have to bring the ruby and saphire to Bills friend on one island. You can now travel to all the sevii islands. Go to four island, go to icefall cave and find the pike all containing it after a small maze. You can use it on the waterfall outside the cave and find Lorelli, after helpin her you can also battle the elite four again. Hope this helped :)
You find the HM7: Waterfall in Icefall cave on island 4. go to the right on island four, use surf to cross the pond/lake and enter the cave from there. Inside Icefall cave you also find nevermeltice. Try the link below to a walkthrough on youtube (not mine). This video shows how to get it.
On six island there is a cave called dotted hole but to get in you must go to four island and go inside icefall cave find HM7 waterfall and use it to go up the waterfall then you will go to the ladder and find lorelei now beat the rocket then go to six island now you can go in dotted hole only if you use cut on the door.
Go to four island and go in icefall cave find HM7 then use it to go up the waterfall go to the ladder then defeat the rocket talk to lorelei then leave and go to six island go back to the cave and the guy will not be there use Cut to open the door.
Go to four island and go in icefall cave find HM7 use it to go up the waterfall go to the ladder beat the rocket talk to lorelei leave and go to six island and go to the ruins the scientist should be gone use Cut on the door to open it.
In Pokémon Ruby Sapphire and Emerald versions, HM7 contains the move waterfall. You can find the HM in the Cave of Origin.
Head to four island go in icefall cave find HM7 use it to go up the waterfall go to the ladder save lorelei go back to dotted hole use Cut on the door and your inside.
go to fogu.com/hm7 and it will tell you