Please note that this story involves some transgendered themes. (main character switchs bodies with the super girl in order for her to use his body to save her world and he to use her body to save his.)
Seems to be some differences between this Supergirl and DC comics version. I will let you read to see them. however flight, strength, speed are all there. First chapter is some background and introduction. Small super feat towards the end. 2nd and 3rd chapters is where you start seeing more.