WHIRLWIND EXPLANATION: Pokémon have a fixed, permanent score from 0 to 31 for each stat that affects how good that stat can ever get.

This calculator will figure out that score (called a "gene" or, more obtusely, an "IV") for you, so you can discard the unworthy. It's more accurate for higher-level Pokémon, so it's helpful to go into a level 100 wifi battle with someone and check your Pokémon's stats from there.

Stat calculator

Arcanine
Arcanine 		Base
stats		 Stats Effort Possible genes (IVs)
Level
HP 90
287–317
31
Attack 110
222–253
31
Defense 80
163–194
31
Special Attack 100
203–233
31
Special Defense 80
163–194
31
Speed 95
193–223
31

Congratulations, you've narrowed your Pokémon's stats down exactly!

This Arcanine's Hidden Power inflicts Dark damage, with 70 power.

And for your copy/pasting pleasure:

31 HP; 31/31 Physical; 31/31 Special; 31 Speed

or start over