Why would they fight? Well, remember when Akane ate that super soba, she went
out and challenged everybody, so Akane sparring Ranma would be something that
is possible. I think that at times, Akane wish she had Ranma's abilities, and
now she does, she would be wanting to show them off. Most probably by teasing
Ranma, and making him feel what she felt like everytime they sparred. Ranma,
being too macho, would never turn down a challenge, so they fight. Here's a
senerio of what is most probably going through their minds...
if you want to use this, sure, go ahead. I had to fight back the urge to make
Ranma yell at Akane, "Woo Wee you good looking!" Yeah, I saw Face/Off. John
Woo is kewl!
********************************************
Akane stood in awe. As she looked at Ranma, she could swear she was looking
in a mirror. She stepped back. Ranma felt the same. The two had switched
bodies.
  "It's like looking in a mirror, only not..." Ranma said.
  Akane regained her pose. "Hey, Ranma, let's spar!"
  Ranma facefaulted. "What!?! We got to find a way back to our normal
selves!"
  Akane frowned. "Don't tell me your affraid of losing?"
  Ranma sighed. "Fine... one quick session!"
  Akane smiled, than leapt to the dojo, except, she found herself on the roof
of the Dojo. "Opps..." she said. "I'm not used to this body. It's so
powerful. I better watch my step," Akane thought.
  Ranma was wearing Akane's body, and changed into her gi. Akane on the otehr
hand, who had ranma's body, had splashed herself with cold water so the body,
even though not hers, would still feel atleast better than the guy form. The
difference Akane noticed was the center of balance, and so she used Ranma's
girl form. 
  Ranma stepped back, rotating her shoulders as she stood battle ready.
"Damn, this body isn't that much differnt than my boy form," ranma said
outloud.
  "Grrrrrrrrr..." Akane relaxed. "I'll show him," she said to herslef.
  Akane found her new body total user friendly. Every move she ever wanted to
make, was at her disposal. She performed a thriple back flip with no hands
with the greatest of ease. Ranma sighed. 
  The attack was on, as soon as Akane landed from her test move, she dashed
at Ranma. Ranma steped to the side, and noticed a lag time. The body Ranma
was borrowingwas slow, and the attack hit Ranma in the shoulder. 
  "I can do this!" Akane said to herslef!