This uberasm code allows you to change between vanilla player and a custom player.

To use it, first you must insert the GFX and palettes used by the player using Dynamic X, 
the GFX must use the same format of vanilla player. Then open the asm file and change the
following constants:

;GFX installed with Dynamic X that are used by the custom player
!PlayerGFXResource = !ResourceGeno

;Palettes installed with Dynamic X that are used by the custom player
!PlayerGFXPalette = !ResourceGenoPal
!PlayerGFXPalettePlayer2 = !ResourceGenoPalPlayer2
!PlayerGFXFirePalette = !ResourceFireGenoPal
!PlayerGFXFirePalettePlayer2 = !ResourceFireGenoPalPlayer2

You can find the Defines of your custom player resources on the file DynamicXDefines.asm.

You can read the code to understand how to change between players, I recommend you check the code
below .Geno label