You can't, you must trade from Emerald (which had an event to get to Mew), or trade from Pokemon Ranch (if you unlocked it).
No Pokemon game has cheats sorry.
no
cheats
you can get arceus cheats
you don't
train in wild Pokemon battles through out the game
There is no possible way without hacking or cheating. I heard they are bringing Mew back in Pokemon Heart Gold and Soul Silver.
no
yes with action replay i think
You have to trade it from soul silver to heart gold this is the only way
You need to get a action replay at a store.
it is impossible except for when you have cheats in Pokemon pearl,platinum,diamond