I suggest heading over here:
http://www.pokemon3d.net/resources/
It contains resources for the game.
Essentially there are two main resources that modify the game in different ways.
Game modes are different ways to play pokemon3d, these can range from simple modifications such as Nuzlocke or complex stories such as silver's soul. These are essentially different games using the poke3D engine. Gamemodes that aren't kolben, are strictly for fun and not for multiplayer access. You will also have to create a new save for each game mode.
Content packs affect the look and feel of poke3d, ranging from texture packs to music packs. These packs are more aesthetic and don't actually affect how the game is played, just how it looks.
Ill link you to the how to for installation and stuff as well.
http://www.pokemon3d.net/resources/9/
