The Costume.

"The shirt will probably get ripped if I end up in combat, can I borrow your costume?"

"Okay." Power Girl sighs. She begins removing the costume, starting with the cape and belt. She then takes off her boots and gloves. She then slips out of the tight, leotard. Supergirl can't help but admire Power Girl's naked body, before remembering that she now shares the most impressive part. Supergirl takes off her skirt and panties before attempting slipping in to the costume. Power Girl puts on her bra and panties before noticing that Supergirl is stuck.

"A little help?" She says, attempting to pull the fabric over her breasts. Power Girl stands behind her and pulls the costume over her. "Thanks. It's a lot trickier than my costume."

Power Girl continues getting dressed while Supergirl dons the rest of the costume.

"Wow!" Supergirl says looking in the mirror, "I look just like you!"

If it wasn't for the longer hair, they would be impossible to tell apart. Especially now that Supergirl is able to fill out the cleavage area on Power Girl's costume just as well.