Pokémon Omega Ruby and Pokémon Alpha Sapphire announced

Huh, someone pointed out something that I noticed but didn't really think anything of:
The Pikachu shown in the artwork has a female notched tail, but it is also black and has a heart shape. That goes past the notion of this just being a cosmetic costume thing, it's a physical design change.

So it is either:
A special event pikachu like the Notched Ear Pichu that is female and has a special tail

OR

The 5 costumes are actually different forms completely, that change aspects of the Pikachu itself.

I'm hoping it's a design change, it looks much better that way! =o

EDIT: Or well, what I mean is that I hope they just decided to flat-out update female Pikachu to have that black heart on its tail from now on.

But I guess it could definitely make sense if it was a special event Pikachu.