I enjoyed Sonic Unleashed when it came out, but one issue I always had about the game was the lack of other characters in it. Aside from Tails and Amy, you don't really see anyone else which is disappointing. I understand Sega can't continuously make everyone playable, but they can at least still acknowledge they exist, so I put together my own idea on what could have been done to improve Unleashed (especially if they every decided to remaster it).
First off, Tails role can stay the same helping Sonic with technical stuff and flying him around the world in the Tornado. Knuckles I think should be more involved in the story
because as the protector of the Master Emerald and someone who's very knowledgeable about the Chaos Emeralds should be able to help restore their power. Also Archie Comics had the right idea pairring Knuckles with Chip (Light Gaia).
As for Sonic's friends, you can find them in different locations either providing information to you or giving you tasks/missions to complete.
Amy can be found in Spagonia doing sightseeing.
Cream & Cheese in Apotos getting ice cream.
Rouge treasure hunting in Shamar.
Big ice fishing in Holoska.
Blaze in Mazuri helping the villagers out (She was actually doing this in the IDW comics).
Team Chatix doing their detective work in different locations. Vector in Empire City.
Espio in Chun-nan.
And Charmy in Adabat.
Lastly we could have Shadow show up in random locations to challenge Sonic to a rival race like they did with Metal Sonic in Colors Ultimate.
Anyways, those are just my thoughts, like if you agree.
