Starmie is an 10-pointed star. Since this is obviously meant to be a Staryu, it's simply the wrong color.

you're complaining about the color? o_O

It's really a dildo,not a real pokemon, and all dildos are purple in art.

Since Starmie is a starfish maybe someone cut off Starmie's extra appendages to make more Starmie.

I always enjoy coming across the first hentai image I ever saw.