Skeetendo

Order of the bytes really wouldn't matter since you're using a label anyway, unless you have some sort of loop that is reading things in a specific order.

I mean, creating labels and designating memory is easy. You can do what you're wanting to do very simply, the complicated part is making all of those parts work for the Pokemon. AKA, in order for all those different values to DO something, you have to code functions to make use of them. Otherwise, they're just unused memory locations like any other. Your focus should probably be more on the scope of how you plan to use those things, and how you can integrate that in to your project.

I mean...the comments alone pretty clearly tell you what you'll need to be doing: "; if it's a trainer mon, the item is in the party struct"

At the very least, you're going to need to update the way the game reads and processes trainer parties, particularly by adding a field to the trainer's 'mon data and passing that value to the appropriate field. You do realize that the held item in Gen 2 reads from the same value as the catch rate in Gen 1 -- this field actually serves no purpose for an already captured Pokemon, so you could just canibalize this section of the WRAM and save yourself a byte. not to mention, you're going to have to program in-battle effects for every type of held item you want ... it's going to be a lot more than merely "converting the code", although reading and thoroughly understanding pokecrystal's code is definitely going to help the picture become clear for you.