Apparently, Amy is very acrobatic in this universe so it actually makes sense. i think it's on the official website.

Technically, tails and knuckles need a flat area to start flying,tails needs to be on a solid piece of land to start flying, he just can't start to fly after the ground beneath him is gone, the same go's for knuckles, plus with his new size, pretty sure his gliding might be taken out. sonic falls on his face all the damn time, so who cares.