First, you have to go to the Multi Battle room and have 2 eligible Pokemon participate. If you've helped Buck before, then he will appear in the Battle Salon. Press 'A' on him, then answer 'Yes' to all of his questions. You will battle alongside Buck. He will only attack the opponents, giving you a perfect chance to inflict heavy damage on his Pokemon.
Battle Tower.
in the battle tower in the not with a friend multi battle room (by yourself)
He's another partner in the battle tower multi battle
anything you want! it's not the end of the game when you do it
Battle Tower.
after u help him he goes to the "battle tower"
buck is in the battle saloon at battle tower.To get there talk to the lady at the far right and say no when she says (would you like to communicate with a friend and form a tag team?) :) i think he is in survival area
You can find her in the Battle Tower multi battle room
After you speak with Buck and he says he will put the Magma Stone back, you will next see him in the Battle Tower. If you select the Multi Battle option, Buck will be one of the trainers you can team up with.
he shows up in the game when he feels like it and one of the partner choices in battle tower doubles
you cannot ever beat the battle tower. but if you have completed the sinnoh pokedex then the battle tower will help you complete it. you can battle at the battle tower as long as you want.
Mo battle tower