You don't need the rarest or the most expensive mount to shine in the centre of your faction's capital city. You just need the appropriate clothes. Someone perfected this with an awesome Super Mario look.
Sniping the "Mario" name must have been the hardest part of this virtual Super Mario cosplay, since it doesn't have any alt code characters (it's not MärÍő or MárłÓ), and the chances that no one's using a simple name such as Mario on any server are pretty low. The rest of it is just a smart combination of gear transmogrification and character class selection.
To get the same results you'll need to roll a male Gnome Warlock, with a moustache, of course (it has to be a Warlock so you can wear cloth gear), and get the Whitemane's Embroidered Chapeau, the Laughing Skull Shoulderpads, Blue Overalls, a simple Red Linen Shirt, a Nightsky Sash, Consortium Gloves and Bright Boots. And finally join or make a guild with the proper name, like "Super Mario Bros." in this case.
And the best companion pet for Super Mario? The Ravasaur Hatchling a.k.a. Yoshi!
Or get the Green Primal Raptor mount if one Yoshi's not enough: