I posted this over in how do I, and did not get an answer so I thought maybe someone here could help...

I have done few Monster High cakes.Just use electric  pink, electric blue and purple from Americolors, they are great . For the skull this is what I did- I printed it out on a regular paper , cut it out and used it as a template on a black fondant( base) then , I cut just the white parts and placed it over the black base ,same thing with the pink ribbon . Also , I use corn syrup to glue small decorations .I hope it makes sense .Good luck!

AFor the pink, I would use a basic pink food coloring which usually yields a bright pink. Maybe even add just a small amount of yellow to kick it up. I would avoid the red or purple in it because it will dull out the color and that pink looks pretty bright.

As for the purple, if I am not mistaken, the violet is more of a bluish purple. I would mix it with pink instead of red and then go with just a bit of black to get the deeper shade. These are just my guesses and I am better with buttercream than fondant/ gumpaste, but I hope that helps you some.

Thanks for the input, Here is my plan, I have printed 2 skull's off google images for the skull I cut one a little smaller then the other, with the bow thought about painting one on but my soon to be 9yo wants me to make a fondant one and put it on, how long dose corn syrup take to dry? I'm going to make some MMF here in a bit and make the skull tonight I haven't decided yet if I will cut the eyes and nose out of the white or cut them out of black and stick them on, that will be set to dry were having the party on Sunday,
Saturday I'm making a 2layer 9 in. cake that I'm going to cover in the dark purple fondant then I'm going to put pink and blue diamonds around it with some white buttercream for the stitching, like the 2nd tear in the picture with a blue strip around the bottom then I'll put the skewered skull and a monster high doll sitting on top.