Pokémon Platinum Version Glitches

Permanently Trapped on Meister Island
This glitch works on Meister's Island on Route 226, where you can trade Finneon to a trainer there to get Magikarp.

In order to do this your party must not contain any pokemon capable of learning surf (other than Finneon), fly or teleport. You must also not have any fishing rods at all and either no rare candies or not enough to make magikarp evolve.

If you go to Meister's Island and trade the finneon for a Magikarp you're now trapped on Meister's Island permanently. Be sure not to save if this happens or else you won't be able to do anything but start a new game file.

If you do happen to have a fishing rod you can make your pokemon fight until they all faint, at which point you'll be transported to a pokemon center.