For my daughter's 5th birthday party, we held a pony party that would make Pinkie Pie proud, complete with pegasus wings, unicorn horns, and Wonderbolt themed capes.
Pegasus wings, Unicorn horns with ears, and Wonderbolt capes
Activities / Games
Princess Celestia's Cloud Painting (sidewalk chalk paint), Rarity's Cutie Mark Boutique (face painting and MLP coloring), Fluttershy's Everfree Animal Toss, water slide
What People Ate
Pinkie Pie Party Mix, Fluttershy's Bunny Food, Apple Jack's Apple Pie Pops, Rainbow Dash's Sonic Fruit, Cake
What People Drank
Twilight Sparkle Magic Potions