Well anyway, the formula I ordered is here, so here

Damage = ((((2 * Level / 5 + 2) * AttackStat * AttackPower / DefenseStat) / 50) + 2) * STAB * Weakness/Resistance * RandomNumber / 100

Seems long and confusing? Compared to the other formula's, this one is easy as pie. Let me explain all the variables first. Damage is, well, damage, the output number. Level is your Pokemon's current level. AttackStat is your Pokemon's Attack/Special Attack stat, whichever one is being used at the moment. DefenseStat is your opponents Defense/SpecialDefense stat, depending on the attack your Pokemon is using. AttackPower is the power of the specific move you're using. For example, if you were to have been using Thunderbolt, you would have a 95 for this variable seeing as in the status screen, there's a 95 clearly marked in the move description when you select it. STAB is the same type attack bonus. If you're using a move that coordinates with your own type, you get a 1.5 bonus here. Otherwise, this variable is equal to 1. Weakness/Resistance depends on if your move was super-effective or otherwise. This variable could be 0.25, 0.5, 1, 2, or 4 depending on how effective your attack was. RandomNumber is simply a Random Number between 85 and 100.

Now let's use this formula. Say I wanted to see the effectiveness of Umbreon's bite on an Espeon (I'm using neutral-nature maximum stats for this example). The Pokemon are both level 100. Bite's attack power is 60. Lets say the Random Number is 100. Now let's plug in all the numbers:

Damage = ((((2 * 100 / 5 + 2) * 219 * 60 / 289) / 50) + 2) * 1.5 * 2 * 100 / 100

Damage = ((((42) * 219 * 60 / 289) / 50) + 2) * 1.5 * 2

Damage = (((1909.6) / 50) + 2) * 1.5 * 2

Damage = 44.9

Damage = ~45

I think this is right

Source(s) Serebii

Hope I helped

//Jofly