In my opinion, Hidden Power should be as the name implies...HIDDEN. Anything that requires you to either hack, calculate, or otherwise do something outside the game to gain or find an advantage ingame isn't worth it. This includes Hidden Power, EVs, and IVs. --- http://img8.joyreactor.com/pics/post/earth-stonehenge-easter-island-703758.jpeg
HP is what keeps your Pokemon alive. When a Pokemon's HP reaches zero, then they faint and become unusable until they are revived. You can get the HP you want by having your Pokemon have the right amount of IVs and EVs in HP.
Damn it Was gonna say this --- RETURN OF THE LAUGH!!! MWUHAHAHAHAHA!!!