It doesn't matter if you're playing in-game or competitive, it isn't good. I'll be focusing on competitive here, but if you want I can add a part for in-game as well.
Chandelure is far too slow and far too strong to use it. Max 284 Speed is not that fast, and that base 145 Special Attack is far too hard to ignore. Chandelure functions best as a wallbreaker with its Hex set or its Choice Specs set, or a sweeper with its Choice Scarf set. Why use an inconsistent move that's very easy to play around if you naturally OHKO or 2HKO every neutral hit and 2HKO or 3HKO almost every resisted hit?
Here are some sample sets for you if you want to use Chandelure:
Chandelure @ Heavy-Duty Boots
Ability: Flash Fire
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Fire Blast / Flamethrower
- Hex
- Toxic
- Protect / Taunt
Chandelure @ Choice Specs
Ability: Flash Fire
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Overheat
- Shadow Ball
- Energy Ball
- Trick
Chandelure @ Choice Scarf
Ability: Flash Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Fire Blast
- Energy Ball
- Shadow Ball
- Trick