[Help] Calculate pokemon damage

[Littleroot]

i'm making pokemon battle system (r\s\e style),
and i dont know how to caculate the damage.
for example - the pokemon is level 5, 'CUT' attack has 50 power,
the pokemon's attack is 12, the wild pokemon's def is 9.
(i dont know if it's matter, sp. attack 9 and wild's sp defense 11).
the wild pokemon is level 3 (again, it's example).
the attacker pokemon have a ability that makes normal moves
(like cut) +3 damage (15 attack), and the wild pokemon have 17 hp and used defense curl that added his defense +3 (i dont know exactly, but...)
this is was the example, how can i caculate this damage?
thank you =]

 

[Satoshi Ookami]

Oh god... you really want to know? :D

Oh well... here you go:

STAB is the same-type attack bonus. This is equal to 1.5 if the attack is of the same type as the user, and 1 if otherwise.
Type is the type effectiveness. This can be either 0, 0.25, 0.5, 1, 2, or 4 depending on the type of attack and the type of the defending Pokémon.
Critical is 2 for a critical hit, 1 otherwise. For Pokémon with Sniper, it is 3 for a critical hit.
other counts for things like held items, field advantages, and whether the battle is a Double Battle or Triple Battle or not.
rand is a random number from 0.85 to 1.00.


All credit goes to bulbapedia.

 

[Littleroot]

Thank you =]
i'm using GM 8, hard than rmxp (no classes, need to make everything from 0 - even walk and simple things like that) :) .