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

Aerodactyl
Aerodactyl 		Base
stats		 Stats Effort Possible genes (IVs)
Level
HP 80
267–298
31
Attack 105
212–243
31
Defense 65
133–164
31
Special Attack 60
123–154
31
Special Defense 75
153–184
31
Speed 130
262–293
31

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

This Aerodactyl'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