Cinderace. It almost seems unfair to compare the two. Cinderace is much faster and has an assortment of coverage options in combination with a STAB boost for every single move. On the other hand, Entei's movepool is pretty lackluster, with just a few coverage options and Howl being its only way to boost its Attack. There is no reason whatsoever to justify using Entei over Cinderace.
Cinderace @ Heavy-Duty Boots
Ability: Libero
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Pyro Ball
- U-turn
- High Jump Kick
- Sucker Punch
The boots are a must have, but as far as the moves go, Cinderace has so many other options as mentioned. Gunk Shot to easily take down fairies like Clefable or Tapu Fini, Zen Headbutt to 2HKO Toxapex, or you could even go for a Bulk Up set at the cost of one of your coverage moves.