[Another one - games and reconstruction] is not known: Smogon de Pokemon Moveset Shuckle of the EV problem?

Pokemon. 248 Def/8 SPD HP/252 now that I program to do but who is the point of the HP of possession 248? I do not know because smogon he would put this. I do not know because possession 252 would damage really much. In smogon they say that you took him you have 248 because these are all the need shuckle. Each knows why?