Concept art i made for Darkspine Sonic.(items and stats in the comments) : r/SonicForces

If there were a form of Sonic that included all previous forms

Sonic Frontiers

Sonic The Hedgehog Series (Alternate Timeline)

What is the difference between Base Sonic and Super Sonic? - Quora

Sonic Heroes The Chaos Project: Sonic the Hedgehog

Sonic Forces Reprisal, Fantendo - Game Ideas & More

Darkspine Sonic/Gallery, Sonic Wiki Zone

Sonic Forces - New Concept Art Screenshots

What is Sonic's fastest form? - Quora

Sonic Frontiers (Video Game) - TV Tropes

How does sonic turn into Dark sonic? - Quora