you can either start with him get an action replay trade and if you have the third evoltion of chimchar get a ditto and put it in day care hope I helped sorry if I didn't
Turtwig (grass) Chimchar (fire) Piplup (water)
you cant see a chimchar in Pokemon diamond so you are saying that no trainer in the game has a chimchar
Chimchar evolves twice in Pokemon Diamond Version. From Chimchar to Monferno to Infernape.
Chimchar is on of the starter Pokemon in diamond. As far as I know, you can't catch a chimchar in the game, but if you want one and didn't choose chimchar as a stater Pokemon, you could trade with someone for a chimchar of WFC.
Chimchar
You must breed a Monferno or Infernape with a Pokemon to get the chimchar egg.
You can get a Chimchar if you trade it from games Diamond, Pearl, and Platinum.
You can't. However, Chimchar can be found in Pokemon Diamond, Pearl and Platinum.
Monferno
you can get it as your starter Pokemon
Chimchar
The starter pokemon for Diamond and Pearl are Turtwig, Piplup, and Chimchar.