For Pokemon, you can't really. You could trade in a high level Pokemon or if you have WiFi, you can "create" a Pokemon and send it to your game at this fantastic website: Pokedit.com
But cheating necessitates altering the coding somehow and I'm guessing from your question, you don't want to spend money on an Action Replay or something like it. That website is truly a fantastic website for you, though. As long as you can access the global terminal within the game, you can send any level Pokemon, with any nature, move, ability, or boost the contest "cool, beauty, smart, etc." attributes.
no you can not its a cheat only for action replay by:grimreaper 1343
"""""""""""""" use action replay """""""""""""" use action replay """""""""""""" use action replay """""""""""""" use action replay
Yes by making a action replay cheat code. Yes by making an action replay cheat code.
action replay
no you can not
An Action Replay (AR) Is A Cheat Code Device For DS
An action replay is for cheat codes used for ds games
there is a master code cheat to use the cheats in the action replay with out it the codes wont work
there is no cheat...
what is the action replay cheat on Pokemon diamond for run through anything
you need a action replay cheat code and the action replay.
The best thing to do is to just get an action replay.