The given Speed EVs let Diancie outspeed Jolly Excadrill in sand after a Rock Polish as well as neutral-natured base 115s with maximum Speed investment at +2 Speed in its pre-Mega forme. 32 Attack EVs allow Mega Diancie to OHKO physically defensive Zapdos after Stealth Rock. Maximum investment in Special Attack with a Rash nature makes Mega Diancie as powerful as possible, while the remaining EVs are put in HP to add a little amount of bulk. A Naive nature can be used as well, enabling Diancie to outspeed threats such as Keldeo, Landorus, and Garchomp after Mega Evolving if this is preferred over the sheer power a Rash nature offers.