May I reccomend you something? Why don't you post your hack at Project Pokemon forums? I am saying this because Project Pokemon is a NDS hacking community so you will get more replies and comments about your hack as well as any bugs the players may find.
As for the Hex editing part sadly I'm not really in a position to explain the hex editing as I'm still learning. You should be able to find some stuff out by looking at the tutorial/research & development sections of the Emulation threads, or try asking someone with more experience. Sorry, I wish I could've helped you out more there.
Hi, I am going to make a Black/White Slideshow Showcase hack. Can you tell me what tools did you used to make your hack and possibly link me to them? Also if you did some Hex Edits, can you tell me about it?