Here are the ways you can get a Growlithe in Platinum:
* Trade from FireRed: This is the only way to obtain a Growlithe without cheating or using glitches. Trade a Growlithe from your FireRed game to your Platinum game.
* Wonder Trade: You can sometimes get lucky and find a Growlithe through Wonder Trade, but this is entirely random.
* Breeding: You can breed a Growlithe with a compatible Pokémon in Platinum if you already have one. Growlithe is compatible with Arcanine, Vulpix, Ninetales, and other Fire-type Pokémon.
* Cheating/Glitching: Using cheat codes or exploiting game glitches is possible, but is considered unethical and may void your save file.
Remember: There are no wild Growlithe in Platinum. The only legitimate way to get one is by trading from FireRed.