Simple. You just battle Candice.
level it up...
route 222 with poke radar
you have to trade him from Pokemon platnium
No you can't the only way is to use AR (Action Replay), trading or pal parking.
At level 32(when it evolves from grotle) it will try to learn earthquake. This is super effective and will be almost a one hit KO!
use cheats or trade
frosslas
You can get him only by trading with someone that has White I have white and i traded my lucario throught the GTS and in return i got a Reshiram
You must use a dawn stone on a female snowrunt.
after you beat the elite 4 you go to the cerulian cave and navagate the maze to the very last floor where you will find a level 70 mewtwo
Ash is not in platinum..
You cannot find Lugia in Pokémon Platinum.