Multiplayer, a key aspect of Pokémon. Using the DS's multiple techniques, there are many schemes for battling and getting friends. Union Room, WiFi Connection. It's all possible. However, so you can differenciate the people you're battling, especially in the Union Room and your Friend Roster in the Pal Pad, the game allows for you to have an avatar. In past games, these avatars were determined solely on Trainer ID. It is the same here, but with a twist

If you go to Oreburgh City and talk to the trainer in the Pokémon Center shown here, he will give you options for Trainers to change your persona to. Once selected, this persona will appear on your Friend's Roster when you next connect to them and will be your sprite within the union room for your friends as well. However you are only given four choices. There are 8 sets per gender. This is what is determined by your Trainer ID. We will create a calculator of sorts at a later date, but below are the lists of trainers in Alphabetical order;

Male

Ace Trainer	Black Belt	Psychic	School Kid
Ace Trainer	Black Belt	Rough Neck	Ruin Maniac
Ace Trainer	Bug Catcher	Psychic	Ruin Maniac
Ace Trainer	Bug Catcher	Rough Neck	School Kid
Black Belt	Psychic	Rich Boy	Ruin Maniac
Black Belt	Rich Boy	Rough Neck	School Kid
Bug Catcher	Psychic	Rich Boy	School Kid
Bug Catcher	Rich Boy	Rough Neck	Ruin Maniac

Female

Ace Trainer	Battle Girl	Beauty	Lass
Ace Trainer	Battle Girl	Cowgirl	Idol
Ace Trainer	Beauty	Idol	Socialite
Ace Trainer	Cowgirl	Lass	Socialite
Battle Girl	Beauty	Idol	Lady
Battle Girl	Beauty	Lady	Lass
Beauty	Lady	Lass	Socialite
Cowgirl	Idol	Lady	Socialite

There you have it. Once you have selected the four Trainers from which you are given the choice, your Trainer Identity will be placed on your friend's Pal Pads in the next time you battle them.