Why is my level 68 female dragonite stronger than level 67 male?(LeafGreen)?

Question

Female Dragonite
Lvl: 68
Nature: Naive
Caught in Safari Zone as Dragonair @ lvl 28

Atk:250
Defense:157
Sp. Atk:143
Sp Def:132
Speed:160

Male Dragonite
Lvl:67
Nature: Jolly
Caught in Safari Zone as Dratini @ lvl 15

Atk: 238
Defense: 138
Sp. Atk: 126
Sp. Def: 145
Speed: 130

I trained them both outside hot spring in one island against fighting masters using VS. seeker? Why is this so..

My character is a male by the way.. Thanks

Answer 1

If you trained both Dragonites against the same foes, the differences in stats is due to the IV's, not the gender.
IVs is numbers given to all Pokemon when caught or hatched. They range from 0-31 and increases the stat of a Pokemon by that number. It will be most noticeable at Lv 100 but it is very much present at lower levels.
Your female Dragonite most likely have better IVs than the male, resulting in it having better stats.
Source: http://pokemondb.net/mechanics/hidden