Restrictions are:  
Sonic has Super Sonic on the jump  
Characters have to be alive  
Either a boosted version of their base forms or base in general  
Prep Time  
So  
1 super form  
1 character that has an army  
1 character with a specific artifact of their own(ME OR Jeweled Scepter is allowed)  
Rest are in base or boosted versions of base(like chaos boost or Neo form)

Shadow(can knock the emeralds out of Sonic and is important to Neo Metal)  
Neo Metal Sonic(boosted version of base metal and can have an emerald)  
Silver(powers are good for this matchup)  
Eggman(full egg fleet)  
Knuckles(with ME)

Basically  
Eggman will create a machine to shut down Sonic’s super form  
Neo Metal will copy the biodata of Shadow, Silver and Knuckles  
Neo Metal will transform into Super Neo Metal with the copied abilities   
Shadow and Silver support him by interfering with Sonic  
Egg Fleet distracts Super Sonic  
Knuckles will give the ME to Eggman to have an immediate chant which shuts down the Super Form

So I have 3 win conditions  
Either beat Sonic with Neo Metal Sonic copying his biodata and becoming Super Neo Metal Sonic with all of the copied abilities  
Or stall long enough for the machine to shut down Sonic  
Or give shadow or knuckles a sneak opportunity to kick the emeralds out of Super Sonic

To make this more interesting