Suggested by Sonic Amy has a degree of super speed and is skilled with her hammer so I don’t want to say that this will be a stomp or anything like that. That said, Dawn still has the edge here thanks to having a wide variety of Pokemon to back her up at every turn. Amy will quickly be overwhelmed at this point and even her speed would be matches during the battle. Dawn wins.
DReager1.com
The Ultimate Fighting/Review Site
DReager1.com 
Empoleon alone might be enough to help Dawn win this.
Empoleon is definitely real strong so that could be the case
Amy is fast enough to catch up to Sonic, and I doubt Dawn or her Pokemon can go as fast as Sonic. Even if a good fight would be put up. So, I wouldn’t count out Amy Rose.
Amy has definitely had some good speed moments there although I feel like Sonic often slows down for her. She should put up a good fight