Go north to Rage lake, battle the Red Gyrados. Go back on shore and Talk to Lance. Follow him back to Mahogany and go to the 'poke mart' there (Its just a building near the exit of Mahogany) and battle team rocket. When you do that you should be able to get into the gym
If you're playing on a cartridge, and the outlook house that would lead to Route 42 (which leads to Magohany) is unenterable, then I don't know what to tell you... Don't feel bad, though, my cartridge had Beta 2 as well.
Once arriving in Mahogany Town, proceed up to the Lake of Rage and battle the red Gyarados. You will receive the "Red Scale" which is then traded to Mr.Pokemon. Then meet Lance (the Dragon trainer) back to town and begin battle with Team Rocket.
Team Rocket and Lance will be found in the "Souvenir Shop" in Mahogany Town.
You have to have gone to the lake of rage and catch the red gyrados (i advise you catch it anyway). Once you have battled it Lance comes up to you and then you go to the gift shop. Once doing this you do this and find a bunch rocket goons. Finish them and the guy in front of the gym should have moved over.
http://www.YouTube.com/watch?v=65JxdNotMcc try this video
1st,go to lake of rage to catch Gyarados (if u cant catch its okay..) :3..and then u
will find "LANCE"there at lake of rage. complete the mission to unlock blackthorn
city/mahogany town gym Direction:(up , left , up , right , up , left , down, right,
down, left, up, right, down, left, up and right.FACE TO PRYCE...)
go through Mount Mortar and leave at the east entrance and keep going east
Go through the mountain and you come back out on the route leading to mahogany town
Go to the very right of the city with the 2 towers
clear the radio tower in goldenrod from team rocket grunts
you definitely need help here, so go read everything on bulbapedia and serebii and psypokes, then here is the solution... mahogany town is in mahogany town!
There IS no Radio Tower in Mahogany town
so you can get past the guy in mahogany town
Mahogany Town.
The lake of Rage is located north of Mahogany Town, on Route 43. Mahogany town is East of Ecruteak City.
get to mahogany town
south of the lake of rage
no, but mount mortar is next to mahogany town and near ecruteak city it crosses through a river to mahogany town
after defeating team rocket in mahogany town,go to the radio tower in goldenrod city.
Go north to the Lake of Rage, you can fish for gyarados their. Additionally, hatching a water type Pokemon in mahogany town would be 'getting it in mahogany town'
you have to defeat the other seven gyms to pass to the next city next to mahogany.
It's in the cave between Mahogany town and Blackthorn town