go to the trainer house. you may see him there.
Use a fire pokemon. That's what grass is weak against.
the same way to beat Pokemon PEARL!!!!
Yes you also need to beat diamond as well.
then you beat the game
No. In Pokemon Diamond you can only catch Dialga once but you MIGHT have a second chance after beating the Pokemon League at least once.
beat him with a level 100
make your grass type learn other moves
beat the Pokemon league
you can go after the legendary pokemon, or beat him again.
No, but you must get to a certain point in Pokemon Diamond to transfer Pokemon from Pokemon Ruby.
Figure it out.
get a girlfriend