Username: Weavile96
Game: Diamond
Gender: Male
Trainer Class: Researcher: You choose to research items, how they work, people, and Pokemon. You of course have help from your Pokemon. Who wouldn't?
Pokemon Team:

Alakazam- Smart, Brains, Psychologist

Gengar- Halloween, Ghost, Purple

Honchcrow- Dark, Sidney (He would have this if he came into the 4th gen, most likely xD), again, Halloween
Special Mission:
Your goal is to catch every single Pokemon you can find in Diamond, while using only Alakazam, Gengar, and Honchcrow. You must also raise one rock type Pokemon of choice. Even though you hate rock types, you must catch one, and raise it to it's final evolutionary stage.
Alakazam must learn Calm Mind as
SOON AS POSSIBLE and keep it throughout the whole game.
Gengar must learn Thief or some move that can steal items. For research on what wild Pokemon can hold.
Honchcrow must learn one move that is helpful for research in a way. It must be reasonable.
I believe you can catch Abra and Gastly relatively soon. If not, just hack one in somewhere. Have fun...
Don't wanna be busted for double posting. Here's mah edit:
Can I choose my own Pokemon that I have to use?