That was....boring.
Sorry, but i wasnt impressed in the slightest at the fights. Its not that it was a bad flash, but the fighting was too repetitive. There were too many fights going on at once to even focus one of them at a time. I dont mind all out melees with characters doing 1v1 or 2v2 or even 3v3. But you had 1v1v1v1v1v1v1v1 if you understand what i am saying.
Basically i'll put it like this. Knuckles would fight shadow, get knocked into rouge who gets knocked into tails who then proceeds to fight shadow, who gets knocked back into knuckles which knocks him to rouge and then he'll start fighting rouge. Too many things going on at once made it hard to focus on one character. Dump this new style of fighting. Episode 2 was better, in my opinion.
It also kinda seemed that you spent most of your time with the fights and let the story weaken as this was basically 95% fighting and 5% story. There are enough sprite fighting movies on Newgrounds. Some that are a lot better, but there really aren't a lot of sprite movies with a strong story. Expand the story a bit more in you next episodes rather than trying to impress us with you action sequence.
Next, SOUND COMPRESSION. This flash has a very high file size for something so short. You need to seriously open this sucker up and change the settings on things, because damn.
Now, as for your twists, you categorized it wrong. it isnt a twist because...
*Spoilers*
1) You introduced metal Sonic in the same episode as you decided to link shadow and him as one. That could have been stretched out for A LOT of episodes and later come as a twist.
2) Shadow switching Sonic for metal Sonic isnt a twist. It was a trap. And an Obvious one at that. Also could have been stretched out for a few episodes.
*end Spoilers*
However, one thing i am VERY impressed with is the fact you used an animated Background. Many people who make sonic flashes tend to use backgrounds that should be animated, as a regular non static. The fact you took the effort to use something animated shows skill for detail.
Also, vary your sound effects, because they got too repetitive. Use different sound effects for different actions.
3/5
6/10
-BlackDevilX