I had an idea to promote more players to donate
Opening the Johto Gyms To Veterans Donators ( and +) And Elites Earlier where as Johto Trainers will get it a week later.....
There are also other rules to apply where you can limit the many times they can challenge like once a day...
Another rule could be that they can forced not to fight a gym twice in that week and not to be able to challenge the Elite Four until after the Johto Gyms are opened to the public....