Hackless, NO!
Walk in and save the game then go in and in out
No.
You cannot rematch just any trainer, there are only certain trainers that you can re-battle such as the 4 Elite 4 trainers as well as Alder. Additionally you can rematch the trainers at the Big Stadium and the Small Court in Nimbasa City, you can also rematch Cheren in Victory Road, Bianca in Professor Juniper's lab, Cynthia in her Villa in Undella Town, Morimoto in the Game Freak building in Castelia City and the Royal Unova trainers.
one of the gym leaders give you it
Yes but you have to beat all gym leaders again. look in you pokenav and see if they want a rematch yet.
You cannot.
You cannot.
Well There is no way to rematch the gym leaders unless if you hack it!
No unfortunately :(
No, this feature is only available in Pokemon Emerald.
I heard the walkthroughs from youtube but you can't
Walk in and save the game then go in and in out
You can't rematch them unless you start again
Only on Pokemon emerald can you rematch gym leaders just wait patiently until they want to rematch you then go to there gym find them and battle them.
You have to receive their number in the Pokegear and call the at specific times
you can't but after you go through Stark Mountain and reach the Survival area at the club you can rematch theminside
Unfortunately, you cannot. Once you defeat them, you cannot have a rematch. However, if you want a better challenge, you could rematch the Elite Four. They will definitely level up your Pokemon.