This is real, tested and proven!
Ok, this requires Pokemon FireRed or LeafGreen version, but the Pokemon it's used on can be traded to Ruby/Sapphire, or Pal-Parked into Diamond or Pearl.

First, get a Poke Doll. Then go to Saffron City on your FireRed or LeafGreen version, and go to the copycat's house. (Assuming you've beaten Team Rocket at the Siph Co.) Have her teach Mimic to one of your Pokemon. (She wil only offer to do this if you have a Poke Doll, with you, so make sure you have one.) Then, use an Action Replay code to find a Wild Smeargle. (Or you can transfer the Pokemon to Emerald version and find Smeargle in Artisan's cave. If you have Diamond/Pearl, you can find a Smeargle on Route 212-North, with a Pokeradar.) Use Mimic on Smeargle, and you will learn Sketch for the remainder of the battle. Then Sketch Smeargle's Sketch so that your Pokemon permanently learns Sketch. It would be safe if your Pokemon only knew 2 moves, one being Mimic, before you do this. Once you have Sketched Smeargle's Sketch, go to a wild Pokemon that has a level up move you want your Pokemon to learn. Use Sketch, and tadah! Your Pokemon just learned the move! You could have a Magneton learning Baton Pass, a Kingdra learning Sacred Fire, a Swampert learning Fly.... Imagine the possiblities!

Man imma use that thanks!!!

i might take a look at it...

how can u have a Magneton learning Baton Pass if it dont have skecth

it cant

zan u make me laught he just explained how lol

haha its true, might be to get his post # up.. idk...

i need action replay cheat code for pokemon diomond

funny how dom post here more than anyone yet he claims he doesnt hack:|