one can be found in hearthome city, and the other you have to breed Pokemon in the day-care to get eggs
All over the place. But you have to trade, transfer, or hatch eggs for some.
you have to catch all of the pokemon in diamond or SEE all of the pokemon
alot...all Pokemon with genders can have eggs well i don't think that cressila and heatran count though. no legendaries or genderless pokemoncan have eggs.
get an action replay then get the "poke mod" otherwise known as Pokemon modifier and then find all the Pokemon.
You can find number 45 almost an where in Pokemon diamond and all you have to do in smear some honey on a tree and get number 45 which is the Pokemon Burmy that evolves into Wormadam
You can't really find them all in diamond, but you can either trade, or migrate from others games. Hope that answers your question
You can't. But you could migrate from diffrent regions
You can find the codes for that on supercheats.com or gamespot
You find a soothe bell at the Pokemon mansion
You travel all over Sinnoh and then trade and/or migrate from other Pokemon
If you have a action replay, you can use it. Or if you have Pokemon pearl,you can find Palkia,if you have diamond find Dialga
all except for legendary rotom, manaphy, and maybe latios and latias can mate