nothing except train your Pokemon and trade and battle with friends. You can also connect to Pokemon revolution
no
Why would you think that? Of course not. actually, neither do, i have tried and i have not gained any boosts of any kind on boy or girl Sources: i have completed both diamond, pearl and platinum, and collected every Pokemon. i am a ": Pokemon master"
Many people think that after you beat the Pokemon league and your rival, you completed the game. To finish the game totally, get every Pokemon in the kanto and national pokedex and beat the Pokemon league. It's a real challenge!
you will know it by catching every single Pokemon in the game and by finding all the Pokemon if you found and caught everything then go to prof. oak or prof. rowan.
no
To finish the sinnoh dex (Pokemon platinum's,diamond, and pearl dex) you just need to see every Pokemon not catch every Pokemon.
you can find them buy trading or getting into the battle zone then going into stark mountin you will find some there. I know because i have completed every Pokemon game but im on the verge to comleting platnium
You can get Pokemon from the older versions on Pokemon Platinum, but I'm not sure if it includes every Pokemon from every game. You'll need to finish your Pokedex, then get the National Dex.
every pokemon from that game and generations before
battle trainers or catch the Pokemon
by using action replay
go to serebii.net