It depends on the gym. Most have requirements that have to be signed off on by an adult before they let a minor into a gym. There are also certain equipment and facilities that cannot be used by minors due to liability issues.
You have to be 18 years old to join Gold's Gym. Some locations allow minors if they are accompanied by an adult.
The target demographic for a gym varies widely, but the majority of gym goers are over 18, who have an active lifestyle.
beat Giovanni in saffron, beat the 7th gym finish the quest on the islands and go to viridian city. the gym over there is the 8th gym.
If your over 18 you could get a gym membership and hire a personal trainer. Its also really important to have a healthy diet, so you could get someone to help with that too
after beating the 1st gym head over to heart home city there is a gym there go inside if you want to get to the elite four!
you have to be 14 to train, but 18 to actually work in a pro wrestling business.
well, you go back into the third gym. and in one of the places close to the gym is where you can get him. after you beat the game and trade over celibi.
go 2 the last float in he gym on the left side
you go to the right and slide all the way over
You go to Ecruteak City, then head over to Mahogany Town which south of the Lake of Rage. The gym is on the south side there.
you go to sunnyshore city but don't go to the gym go to the lighthouse and you will find the gym leader talk to him and then he will go back to the gym so you can fight him
Fantina is in the contest hall. Go there and talk to her. Then go back to the gym and she'll be there!