(Please read the description to understand a bit ( T_T)＼(^v^ ) )
After Sonic's decision, Shadow and the others decided to take him with them to the planet Byzanthus so they could begin the beginning of their plan and train Sonic properly to get him used to the universe,with Shadow acting as his coach. They will also have the opportunity to stay in one of the large bases of the Rebellion against the Empire, and from there their plan will begin: They will have to try to stop the public tax market and have at least 65% of the Master's army troops move away(The Sonic commander of the empire they call him Master for his personal law :‑X),then try to enter the fortress and look for the Master,and with Sonic's new help kill him once and for all,and free billions of planets and galaxies from the forces of the Empire.
finally after a few days of travel on the ship they land in the port of Byzanthus,ready and charged to start planning the plan down to the smallest details.(To remind you of Tails, Amy and Knuckles there are some details, Tails doesn't have a body and is a hologram, Amy looks a bit like the robotic Sonic Prime, and Knuckles the same I would say, but with more human parts)
Sonic, Shadow, Tails, Amy and Knuckles get off the ship. They are greeted by the Rebellion's helpers.