Mature Tinies Than Can Definitely Fit Into Barbie Shoes?

I think the Maskcat tinies would as their feet are very small - they are flat feet though. I have a Maskcat doll but no Barbie shoes to try to test out unfortunately.

 

Yes, Maskcat tinies can fit some Barbie shoes. Not all, though.
Her feet are very small, smaller than a barbies and that's what makes it work, considering that barbies have soft feet. Any hard plastic foot, even if it was identical to a barbie foot in shape, would have problem with most hard plastic barbie shoes.
The ones that work best are the flat shoes made for heeled barbie feet, like sneakers. Some of the high heel pumps does work as in they can be put on and sometimes the doll can even stand in them, as the ankle joint of the maskcat is pretty reliable and have a hood range, but it will look a bit funny in open shoes, as the maskcat foot is like a normal barbie foot without the toe part, the foot is shorter so it leaves a gap in the front of the shoe.
Be careful with boots, the foot will go in much easier than it will come out and there is a real risk of getting stuck. Boots with a slit up the back is safer, but they usually don't look very nice.