If you have read all the other amazing guides I've written so far, then you probably are familiar with the fact that your stats can be very diverse. Your efforts for those high stats pay off though in an actual battle. But I'm sure you've wondered how actual damage is calculated (or maybe you haven't :P).

But before I throw formula's and stuff at you, lets start with some of the commonly known things. When you have a Pyschic type and you use a Psychic type move that does damage, that move will gain a 1.5 damage bonus, commonly known as STAB. If you've inspected the status screens for pokemon, you've probably noticed that the moves that do damage have some number like "40" or "95" or some other number between 12 and 250. You may have landed a super effective hit on a pokemon, in which that case it does double damage. A non-effective nor non-ineffective attack will not give you any bonus at all, and an ineffective attack will give you a 0.5 attack bonus, which will weaken your attack versus that particular type. There are even some types that aren't effected at all by some types of moves, which is sometimes escapeable.

Now, there are other things that may be a bit unclear to you about damage calculations. For example, the attack/sp. attack and defense/sp. defense stats. How would they actually contribute to doing damage? Well yeah, the higher the stat the more damage you do :P, but there's more to it than just that.

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

You may be saying WTF THATS TOO LOW but that's indeed near what it's going to be. Umbreon's Special Attack isn't that great and Espeon's Special defense is decent, so it makes sense why that number's pretty low. Try it out with a Kyogre's Surf vs. a Magikarp. :P

Oh yeah, you may be wondering how Swords Dance and those attacks up your stats. Well, each of the moves like that will up your stat or decrease your stats depending on the move a number of levels, maximum is six. Say you used Howl and upped your Attack stat by 1 level. What does that translate to? Well depending how many levels you have, those moves will up either your Attack, Defense, Speed, Special Attack, or Special Defense stats by a certain percentage.

-6 levels: 25%
-5 levels: 29%
-4 levels: 33%
-3 levels: 40%
-2 levels: 50%
-1 level: 66%
0 levels: 100%
1 level: 150%
2 levels: 200%
3 levels: 250%
4 levels: 300%
5 levels: 350%
6 levels: 400%
That's basically all I can think of in calculating a move's damage.

Thanks to Dragonair for writing this for us