Sorry, Shaymin's a Legendary Pokemon, and Legendaries can't breed with the odd exception of Manaphy, which give you a Phione.
In my opinion, I think Buneary, Eevee and Pachirisu are good mates for Pikachu.Also shaymin is a good mate for pikachu.
Put them in the daycare
Sorry mate, you can't get it on pearl. It's a Pokemon Platinum item only, you can find it in platinum if you talk to this one lady by floaroma town with shaymin in your party. Sorry I couldn't help much =/
only ditto to make more rotom
A Ditto is the best Pokemon to mate with in Pokemon White.
im sorry but there is not a code
Haha good question. They change their gender when they want to mate.
im sorry but u have to go to toys r us... sorey mate but u have to....
dito can mate with any Pokemon besides legenderys
Not legendaries but mostly all Pokemon can mate with ditto
Yes, there are shiny Pokemon in Soul Silver. But there is a very slim chance that you will run into one. But if you do, then catch it, because shiny Pokemon are very rare. Also, try the Masuda Method. If you have a Japanese Pokemon and an English Pokemon, mate them. There's a better chance of getting a shiny Pokemon than 2 English Pokemon. ( Make sure 1 or both of them have evolved. This will make it easier to mate. )
It depends on whats the gender of the Pokemon and you can mate it with another togetic or any Pokemon that its opposite gender