nothing will happen. you have to catch all the Pokemon to get something. you will get one of the johto starter Pokemon.
YOUR WELCOME
you talk to professor birch and he gives you a jirachi
you get a national dex so you can see even more
Nothing Happens
You see every single Pokemon, Google this "How to see every Pokemon in platinum DS"
No- At least I don't think so! Try every day and see what happens. Good luck!!
nothing, i know from other games ive beaten, if you obtain every Pokemon they just say good job
nothing
Battle every trainer and Trade with Pokemon colleseum
you need to battle every trainer you see
no
see every Pokemon
battle trainers or catch the Pokemon