Different worlds, different rules. In many Tumblr-verses, changelings are effectively a type of pony in the same vein as Earth Ponies, Unicorns and Pegasi. In others they’re an insect race that have been drawing sustenance from ponies for so long that they’ve taken on pony characteristics at a hereditary level. Where I’m from, changelings are a biological weapon.
 
A big thanks to the shout-out from Four Inept Guard Ponies! You can see more of the crossovers with this comic at this link!
 
And yes, I was just being silly about being anti-changeling in the bar. If I was serious, you folks know I would have been wearing very different apparel.