One type of special ability magic called "Aera" allows Happy to temporarily grow wings on his back and fly, but he can only carry one person in this form. Description from fairytailnews.blogspot.com. I searched for this on bing.com/images
Erza's armor names: Heart Kreuz, Heaven's Wheel, Black Wing, Fire Empress, Giant's, Adamantine, Purgatory, Japenese Cloth, Farewell, Lightning Empress, Flight, Robe Of Yuen, Morning Star, Arma Dura Fairy, and Sea Empress. Complex, am I right?