Well action replay is the best way to have cheat codes but if you are willing to risk your profile on the game then......
cheats without action replay are called glitches and if you don't do them right your profile will be wiped out so here are some tips.
USE ACTION REPLAY
DONT TRY AND DO GLITCHES!!!
if you want to try go to u tube and look for Pokemon pearl/diamond tweeks!!
you may screw up alot of times but i got darkrai out of it!!!!!!!!!!!!!!!!!!
Chat with our AI personalities
you can't do that you need a action replay or R4 if you want cheats. or.... you could probably use the events to get legendaries.but i know you can't use cheats without a action replay
No Pokemon game has cheats sorry.
there are a ton of cheats for Pokemon games but i can't figure some out. : (
none
yes. there are AR cheats for platinum.