You can forego all the math and figure out your Pokemon's Hidden Power type by using an IV calculator. We're particularly fond of this one. Simply plug in all your Pokemon's stats and this calculator will tell you what Hidden Power your Pokemon has. Before you start calculating, there are a few things to keep in mind. You'll need to know exactly how many Effort Values (EVs) were earned for each stat, or the calculation will be imprecise. If you're dealing with a freshly hatched Pokemon, you'll want to level it up a bunch to get a precise stat calculation.

Above: Pikachu's coverage benefits greatly from Hidden Power Ice

Now, we bet you're thinking, "This Hidden Power thingie requires an awful lot of thought and work. What's the point?" The point is giving your Pokemon more diverse and powerful abilities. Let's use our surfing Pikachu for example. One of our Pikachus was able to learn Hidden Power Ice. This is a fantastic attack for a Pikachu to know. With a move set of Thunderbolt, Surf, Grass Knot, and Hidden Power Ice, this Pikachu has brilliant coverage. The Ice attack allows it to hit unsuspecting Grass and Dragon Pokemon for super-effective damage. That's the beauty of Hidden Power - through careful breeding or dumb luck, your Pokemon will be able to cover its offensive holes or be prepared for types it's usually at a disadvantage to. This attack can drastically change the makeup and effectiveness of your Pokemon.