Doing this because I'm really amazed this Pokemon even manages to clock 2% usage:
Don't Use This:
Arcanine @ Leftovers
Ability: Intimidate
EVs: 252 HP / 252 Atk / 4 SpD
- Flare Blitz
- ExtremeSpeed
- Close Combat
- Wild Charge
Basically took a look at the moveset statistics to see what the most common set was. Anyways, the fact that this thing manages to even get 2% usage is astonishing. I can see the appeal this thing has; it has a nice Attack stat, a somewhat usable Speed, and okay bulk along with good coverage. However, this isn't enough to justify using Arcanine over any Fire-type available. It can hit fairly hard, but it's a lackluster choice compared to other Fire-types available, especially Entei, Infernape, Mega Charizard X, etc. Yes, it has Close Combat and Wild Charge for Rock- and Water-types, but that isn't something the other Fire-types can't do (other than Talonflame I guess). Intimidate is cool, but not so much on Arcanine, since its defensive typing is rather poor, and most physical attackers have a way to hit it really hard.
Instead, use:
I could make a whole list here but I shouldn't because Arcanine is outclassed by so many things. In other words, if you want a Fire-type, there are plenty of other choices that are better than it. Entei has Sacred Fire, and the high burn chance is neat, while it also has the lovely ExtremeSpeed that Arcanine has. Infernape has good power and Close Combat, making it a better Pokemon than Arcanine in every way. There's also Mega Charizard X, who has Outrage and Dragon Dance along with Tough Claws so it's much more lethal than Arcanine. Talonflame has Gale Wings Brave Bird and U-turn and its revenge killing role makes it a better mon than Arcanine. You should probably get my point by now. There is simply no reason to use Arcanine over any of these Fire-types in OU. Everything Arcanine does, something else can already accomplish or even do it better.
Don't Use This:

Arcanine @ Leftovers
Ability: Intimidate
EVs: 252 HP / 252 Atk / 4 SpD
- Flare Blitz
- ExtremeSpeed
- Close Combat
- Wild Charge
Basically took a look at the moveset statistics to see what the most common set was. Anyways, the fact that this thing manages to even get 2% usage is astonishing. I can see the appeal this thing has; it has a nice Attack stat, a somewhat usable Speed, and okay bulk along with good coverage. However, this isn't enough to justify using Arcanine over any Fire-type available. It can hit fairly hard, but it's a lackluster choice compared to other Fire-types available, especially Entei, Infernape, Mega Charizard X, etc. Yes, it has Close Combat and Wild Charge for Rock- and Water-types, but that isn't something the other Fire-types can't do (other than Talonflame I guess). Intimidate is cool, but not so much on Arcanine, since its defensive typing is rather poor, and most physical attackers have a way to hit it really hard.
Instead, use:
I could make a whole list here but I shouldn't because Arcanine is outclassed by so many things. In other words, if you want a Fire-type, there are plenty of other choices that are better than it. Entei has Sacred Fire, and the high burn chance is neat, while it also has the lovely ExtremeSpeed that Arcanine has. Infernape has good power and Close Combat, making it a better Pokemon than Arcanine in every way. There's also Mega Charizard X, who has Outrage and Dragon Dance along with Tough Claws so it's much more lethal than Arcanine. Talonflame has Gale Wings Brave Bird and U-turn and its revenge killing role makes it a better mon than Arcanine. You should probably get my point by now. There is simply no reason to use Arcanine over any of these Fire-types in OU. Everything Arcanine does, something else can already accomplish or even do it better.