Singles:
Gliscor can use stealth rock to put opponents in Chandelure's KO range, U-turn to switch Chandelure in safely, and defog.
Wash Rotom can use defog and volt switch, and it can switch into water or ground attacks.
Serperior can use defog and threaten bulky waters that counter Chandelure.
Excadrill can use stealth rock and rapid spin.
Greninja can use spikes to put opponents in Chandelure's KO range (and hit volleyballs :P) and sweep after Chandelure takes out enough Greninja threats.
In doubles, I think Chandelure most appreciates drought and tailwind, so a good teammate would be mega Charizard Y.