Kenny 2x4

Here's my own personal way of doing it:
1) Get as many rings as you go along and of course the level ups using Espio whilst dodging attacks wherever possible. 2) When you get to the first "ramp zipper" change to Charmy to lead and then when you are in the air try and start flying a little or control Charmy so that you get the balloon to get a level up. 3) Then, change back to Espio and continue with the rings and dodging. Then you will need to change to Vector to use the gong.
4) Do that and as soon as you land change back to Charmy and take flight fairly near Eggman so that you pretty much avoid the missiles. 5) Start attacking Eggman using Thundershoot whilst still flying and keep on doing this.
6) Hopefully after a while you will have your Tema Blast ready. Use it.
7) Try and continue the Thundershoot attacks.
8) If that doesn't defeat him repeat the steps.