Here's what I recommend For Sonic and Tails' team, use Amy and Big. Amy packs a powerful punch, while Big is a flipping brick wall when it comes to his armour stat, and for me, even outperforms E-123 Omega! For Knuckles and Shade's team, use Shadow for sure. His speed is awesome, and is second only to (of course!) Sonic himself. And for the final teammate, I have always, always, ALWAYS used Cream. She's got luck on her side, especially with her pet Chao, Cheese. But her low damage power is an obstacle in combat, as she can only attack once per round. But it can be worth it (the main reason why I really use her is because she's cute XD). But if you don't like Cream, try E-123 Omega. Like Cream and Big, he can attack only once per round, but according to the Codex, he has the highest damage power and armour in the game. So it's worth a shot, too! Hope this helps!!! Especially with Imperator Ix!! ;D sort of a spoiler if you haven't gotten to Chapter 10 yet ;D
For chapter 10 in the game, here are the teams I recommend: For Sonic and Tails, the other two should be Amy and Big. Amy is pretty strong, and Big's got the highest defence in the game, and is really only able to be matched by E-123 Omega, and not even that bag of bolts can do as well as Big can (well at least for me!) As for Knuckles and Shade, use Shadow (NO MATTER WHAT!!!!), because his speed is A. MAZE. ING. The last character for this team, I always use Cream just because she's cute and with that little Cheese by her side she can help you get at least a little higher chance of an Ambush, and, go figure, Ambushes can be a huge help! Even though she can only move once per Round, Cream is fairly good. But then again, all my characters are Level 22 and beyond (Rouge is Level 29!! O_O). But that's only because I've beaten the game 9times and am on my 10th go!! Have fun and I hope I helped! ;D (this sort of a spoiler btw)
When you are underground I chose Sonic and Knuckles' team as Shadow and Amy. Then Eggman and Tails' team is Cream and Big. Sonic's team needs to be strong because they will be fighting a lot. Eggman's team gets Big as the strongest member so in case of a fight that is unexpected.
In Chapter 10, you head for Kron to have a meeting with other races(Zoah, N'rrgal, Kron, Voxai). In Nestor's Home, Nestor the Echidna can recite your Relics and Tablets for you. After he has all 5 Relics, he hands over the last Tablet, and starts decphering the 1st one;
#1- A race called the Precursors lived in the Nocturnus Realm before Ix controlled it.They left Tablets that showed their studies of the Nocturnus Realm. They soon saw all the races were strong and powerful.
#2-The Precursors thought this realm was a prison, and the races were brought there to suffer.
#3-This Tablet said that a being brought them there. Could it be Argus, a supreme being, who was thought of by prophecies, who took them there?
#4-The time in here is different in worlds. A day in the Nocturnus Realm could be a year, century, decade, millenia, second, minute, hour, week, or month in another. That explains how the Nocturne Clan vanished millenia ago, although they exist in the Nocturnus Realm.
#5-The last Stone says"The Will of Argus, Must Escape Argus" repeatedly. This knowledge was too much, even for Nestor the Wise. As he went into exile, he stated" I won't help you more, for I cannot, my brain has too much to ponder with, and I'll just drag your assault. Until next time, brave young warriors! Farewell...."!
How to open the forcefield in green hill zone in Chapter 4
Added 21 Aug 2009, ID #12325
Go in central city then go into the empty workshop. This time it won't be empty. Talk to the man in the corner of the workshop. After you receive the mission, Go to greenhill zone and to the saleman. He will give you the stapler. Go back to central city and talk to the worker. Then he will give you the very last eggman device. Go to the forcefield and open it.