I guess these ponies are all forms of magic, but here you go...
1. I still want ruby slippers (or, okay, if you're a purist, silver slippers), so that I can click my heels and go home!
2. I want a magic wand! I don't know what it should do. Maybe it does something dumb, like changing a pig to a chicken, or making the person next to me jump as if spinachified, or, oops, dropping something out of my pockets. Or maybe it does something dumb at first, and I have to learn how to use it.
(Maybe even Rogue-style wands, where a wand works only once and you don't know what it does till you try it. Of course, there would have to be some way to shake this up in Glitch, so that communal knowledge does not replace individual knowledge. Maybe what works for me is different from what works for you.)
3. Invisibility would be fun, too. Rogue-style rings, or Harry Potter-style capes? Maybe a temporary action from a wand? Or, like spinach, from a food that you eat? Maybe if you drink invisible ink (which we don't have yet, but should) you'd turn invisible for a bit.
Probably not terribly useful for anything, but potentially fun.
4. Sure, invisible ink is a pony, too. Maybe you have to make it out of bubbles, though of course IRL invisible ink can be made with lemon juice.
5. Potions in general might be better than wands in that they more obviously have N uses. But a potion could be a teleportation potion, or an invisibility potion, or what have you.
6. But I still want a wand. Even if it's dumb.