buy an action replay and cheat. :) I believe that a honest answer would be useful
you have to catch all of the pokemon in diamond or SEE all of the pokemon
look in the cave norh east of solaecean town and look there
in the house near the bottom of eterna city Look for them.
something that starts with a L ive only seen it once on my friends game
get an action replay then get the "poke mod" otherwise known as Pokemon modifier and then find all the Pokemon.
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 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
Look at the related links. The page that it directs you to has a huge table of all the Pokemon abilities and what they do.
You travel all over Sinnoh and then trade and/or migrate from other Pokemon
You can find the codes for that on supercheats.com or gamespot
You can't. But you could migrate from diffrent regions
You find a soothe bell at the Pokemon mansion