I honestly can't think of what toy company would produce ponies that were the Avengers. You said they weren't MLP, and I personally don't know fakie brands that well.
That'd be kinda funny of a fakie company did it, seeing as Hasbro does MLP and Marvel stuff, LOL! But if they are fakies & not customs, if they're collectibles I guess they could date back before the Hasbro/Marvel agreement or just be rip-offs .... And if they are customs, that'd be just weird to see at Citywalk, wouldn't it?
They don't usually have fan-made stuff that I recall (handcrafts, yes, but jewelry / decor that's non-trademark-specific stuff), but I haven't been there all that often or that recently ....
Sorry if I seemed to jump on you, btw! #^^#