@Background Pony #35D7
Throughout the show, Pinkie has shown to have many abilities that normally are impossible for other ponies. A list of these are Superanimal Physiology, 4th Wall Awareness, Enhanced Speed, Teleportation, Pinkie Sense, Enhanced Memory(yet can't even remember her birthday), Enhanced Strength, Armor-like Skin, Using Mane/tail as extra limb, drill, and way to fly(similar to tails), Silly putty-like skin, Control over gravity, Pulling objects out of alternate worlds/her mind, Fitting in extremely tight spaces, Literally falling apart, Having life-like costumes of other ponies, Changing her face structure, Swallowing entire family-sized cakes whole, Breathing without a mouth or nose, and many others. Also, Maud is able to know where other ponies are. Now who else is able to do most of these.
My theory is that Pinkie and Maud are both half-draconequus, that they were adopted by their current family a few years before they got their cutie marks. Pinkie got most of the draconequus DNA, but Maud got 1/3 of it. Maud's draconequus DNA gave her the "Maud sense" and the ability to throw rocks 5 times her size really far. Pinkie's draconequus DNA gave her all of the powers that she has currently.
Before you ask, "If they have draconequus DNA, why don't they have the major reality shifting powers that Discord has? Why does Maud have a power that Discord does not?" I can answer both of these questions.
The reason that they don't have major reality shifting powers is because their draconequus DNA isn't plentiful enough to give them those reality shifting powers. As for the second question, the draconequus that Pinkie and Maud's draconequus DNA had a few more powers than Discord had, one of them being the ability to predict where ponies will be at a certain time.
And that's my theory.