you cant but if you have a action replay then you can do the cheat to get any Pokemon you want at any lvl but unfortunetly (spelling may be wrong) i do not have the code for it
There is no way of getting Pokemon without catching them, unless you cheat.
You Can't
trading!but i would rather catch it.
That is actually possible if you don't feel like catching any pokemon you can have a friend trade you all of them and then you will have the pokedex finished without using any pokeballs.
action reply
You can go into the Pal Park and then leave without catching anything. Sometimes you have to, actually. For instance, if you are migrating some ocean Pokemon and you didn't bring any Pokemon with you that allow you to surf... you need to leave, change your party, and come back.
not unless you have AR {action replay}
Use Gameshark or Action Repley codes
by throwing a pokeball or other Pokemon catching capsule!
Trading, Migrating, Catching the legit legendary Pokemon in pearl, etc.
If it is a ledgendary Pokemon (meaning there is only one of it in the game), them no
look in the Pokemon tower in lavender for haunter. note, haunter is hard to find in the Pokemon tower