Well, there's a really specific pattern to follow to get to the gym leader (across the ice, that is), and for more inforamtion head to this site: http://www.psypokes.com/rs/images/8thgym.png As for him, go to this site: http://www.psypokes.com/rs/walkthrough.php?part=8 It's on the bottom of the page.
Well first you need to bring GROUNDON and KYOGRE together so that they fight. Then you need to get RAYQUAZA so he can break 'em up (he's on rout 131). Next go back to SOOTOPOLIS and Watch RAYQUAZA do his stuff. then talk to the guy in front and you should have full access. =D
It is very complicated. so read very carefully.
1st. Go forward 1 tile then over on tile then up 1 tile then over 2 tiles then up 1 tile then over 1 tile then stand on the stairs.
2nd. Go up to the first tile then over 3 tiles then up 2 tiles then over 2 tiles then down 1 tile then over 3 tiles then down 1 tile then over 1 tile then up 2 tiles then over 3 tiles then stand on the stairs.
3rd. Go on the 1st tile then go right to the rock then go up 1 then right 2 then down 1 then over then up 3 then over 2 then down 1 then over 1 then up 1 then over 1 then down 2 then over 2 then down 1 then over 1 then up 1 then over 1 then down 1 then over 1 then up 1 then over left 1 then up 2 then over 1 then down 1 then over 1 then up 1 then over 1 then down 1 then over 1 then up 1 then over 1 then stand on stairs..
Dang that didn't take long did it?
There you go now go and defeat Wallace.
go through the ice path to black thorn city
Have a kadabra and a couple potions.
The only way to get a gym badge is to challenge the corresponding gym leader and win.
I get my 8th badge in Sootopolis gym.
Petalburg city he's in the gym and you battle him for your 8th badge.
at the gym
the ground gym
Beat the 8th Gym leader.
It's in the gym when you're done defeating the leader he will give you the TM (8th badge)
it's in the woods between the first gym badge and 5th gym badge
Beat the gym leader
Pokemon league
you beat the gym leader
Sunnyshore City Gym: Electric (beacon badge from Volkner)