You may be able to catch it in the Safari Zone. Also another place (providing you have completed the Pokemon league) is Mt. Silver on the grass patch near the Pokemon center. you can also catch it in your pants.
The easiest way is at Mt. Silver on F1, the Expert Belt chamber, Moltres's chamber, the lower mountainside, F2, the upper mountainside, and F3.
catch a high level larvitar lol
The easiest way to find larvitar is to look on route J. It may take a while but you will find it
you can not catch it in pearl but u can catch bagon in pearl
The masterball.
If you are trying to catch ditto in heartgold and soulsilver, I found the easiest way is to catch it outside of the daycare, just south of goldenrod city. It might take about five or six goes, but you will find him. I suggest using a quick ball. Good luck!
There are WAY to MANY to count!
masterball
You can't catch fairies as they do not exist.
The easiest way to get one is to trade a Krabby to a fisherman in Olivine City.
use a poke-ball on it
use a master ball