No to Entei. There are a couple major reasons:
1: Spikes are much, much more common, and saying "stealth rock is less common" is iffy in general, because if the opponent gets SR and 1 layer of Spikes, Entei can only switch in twice total.
2: Sun sucks ass right now. Basically every single weather changer beats Sun like a drum- Hippowdon has enough bulk to take Entei's attacks, Tyranitar just laughs it off, and Politoed both resists and rain-weakens the Flare Blitz.
3: Calm Mind is just... not interesting. 90 Special Attack isn't winning it any awards, and with no reliable recovery, it's not going to last long enough to accrue enough boosts to actually deal interesting damage.
4: The fact that Heatran is basically the best switchin to it possible doesn't really help it, because it can't really leverage Will-O-Wisp that way.
5: Grounded and SR weak makes Eruption trash. Nitro Charge is "ok", but its physical movepool isn't all that stellar, and Nitro Charge itself is weak. Level Ground is doubly weak- 60 base power does not a coverage move make.
6: Mixed Scarf? Really? Its offenses are mediocre enough as-is, and now you want to split EVs? Not buyin it.
Also, a couple other things.
Flare Blitz Entei is locked Adamant, which means it really can't take advantage of its speed that well. That makes the mixed Scarf set even worse, because using Flare Blitz means weakening all of its special attacks. On top of that, it's basically outclassed entirely by Arcanine. It has slightly less bulk, but it has "more speed" due to not being locked into Adamant, more Special Attack, two actually useful abilities (intimidate and flash fire, fuck yeah), the potential for reliable healing in the form of Morning Sun, and most importantly, CLOSE COMBAT HOLY SHIT letting it get past Heatran and Tyranitar reliably.