Hidden Power (HP) is a very usefull move because it can provide a move of a certain type a pokemon might be lacking. It's very hard to get the HP type you want, because it can be anything and everything. First I will be teaching you about how to find the type of your Hidden Power.
Basically it s all about math, a whole lot of math. For HP the Special Defense (spD) IV is the key factor for both typing and power. If the spD IV is EVEN it means that that Pokémons HP is always PHYSICAL. If the spD IV is ODD it means that hat Pokémons HP is always SPECIAL. Below will be the exact math for HP type, which will look like a bunch of bullshit, but I will be providing explanation that's clearer then Smogon does, because it takes a while to understand what Smogon means.
As you may or may not have noticed, Smogon didnt put the stats in the way we are used to, but in order of least important to most important. You can see that special defense has more than 50% of the variables (32/63), which means that if it's odd, your total number will be 8+ (or special), if even it will be 7- (or physical). It is impossible to get a max Speed Hidden Power Fire, Rock, Fighting, or Psychic, regardless of the strength of the Hidden Power (there isn't one for 70 power, 69 power, or 30 power). I cant really give more explanation about this, i can however provide you with all possible IVs that give a certain HP type.
[spoiler] Numbers are in the order of HP/Atk/Def/Spd/SAtk/SDef
Read 31 as odd and 30 as even.
Fire:
31/30/31/30/30/31
31/31/30/30/30/31
30/30/31/30/30/31
30/31/30/30/30/31
Water:
31/31/31/30/30/31
31/30/30/31/30/31
30/31/31/30/30/31
30/30/30/31/30/31
Grass:
31/30/31/31/30/31
31/31/30/31/30/31
30/31/31/31/30/31
Electric:
31/31/31/31/30/31
31/30/30/30/31/31
30/31/30/30/31/31
Ice:
31/30/30/31/31/31
31/31/31/30/31/31
30/30/30/31/31/31
Fighting:
31/31/30/30/30/30
30/30/31/30/30/30
30/31/30/30/30/30
Poison:
31/31/30/31/30/30
30/31/30/31/30/30
Ground:
31/31/31/31/30/30
30/30/30/30/31/30
Flying:
31/31/31/30/30/30
30/30/30/31/30/30
Psychic:
31/30/31/30/31/31
31/31/30/30/31/31
30/31/31/30/31/31
Bug:
31/31/31/30/31/30
31/30/30/31/31/30
30/31/31/30/31/30
30/30/30/31/31/30
Rock:
31/31/30/30/31/30
30/30/31/30/31/30
Ghost:
31/31/30/31/31/30
31/30/31/31/31/30
30/31/30/31/31/30
30/30/31/31/31/30
Dragon:
31/30/31/31/31/31
31/31/30/31/31/31
30/31/31/31/31/31
Dark:
31/31/31/31/31/31
Steel:
31/31/31/31/31/30
30/30/30/30/30/31
[/spoiler]
Lets now do some power math, because you can get the perfect HP type, but if it lacks power, you might as well not use it. It is another line of math just like the type one, but I will try to put an easier version of the same straight under it.
It is in the order of hp/atk/def/spd/spA/spD again, because the spD has the most relevance to the power. You can just follow the math given by smogon, or take a look at what I spoiler below, which will be the exact power gain a certain good stat gives.
[spoiler]
HP gives (+/-)0,635 power
atk gives (+/-)1,270 power
def gives (+/-)2,540 power
spd gives (+/-)5,079 power
spA gives (+/-)10,159 power
spD gives (+/-)20,317 power
the standard: 30 power
[/spoiler]
Once u added all these numbers up, you need to round it down and that's your HP power. spD decides over 50% of the total power again, so if the spD IV isnt one of these: 2, 3, 6, 7, 10, 11, 14, 15, 18, 19, 22, 23, 26, 27, 30, or 31, you might as well not check the rest, cuz that would be a total waste (If the IV isnt in that list, it means a max power of 49, and who would run that?).
I hope I made as much sense with this guide as I feel like I did, if not, please add feedback below!
