I would have argued that Tails should be the 2nd Sonic character, but with how much Shadow has been pushed lately, and him being the most popular Sonic character after Sonicā¦ itās gotta be Shadow.
Itās really a shame how much Tails as a character has fallen off, even in the Sonic 2 movie he was overshadowed by Knuckles.
Honestly, Tails
and Knuckles both fell off after Heroes. The Adventure games gave them their own roles and stories, Heroes let them be part of the main hero team, but after that? Shadow '05 focused solely on Shadow, '06 pushed Sonic, Shadow, and Silver and pushed everyone else into the background, and after that Sega heavily de-emphasized anyone but Sonic. They at least get to be part of Team Sonic in stuff like Boom, Mania, Frontiers, and the movies, but they haven't had a truly
leading role since the Adventure games, aside from arguably the Sonic Mania & Knuckles side mode in Mania. And even then, they're still second fiddle to Sonic in the marketing - Though, the second mvoie heavily pushed Knuckles as a powerful rival to Sonic. That was cool, at least. It'd be nice if he got his own game again.
Actually, Shadow's the only one to be pushed as a second main character to Sonic and actually have it
stick. We already went over Tails and Knuckles. Blaze got to be his equal in the Rush games, but after '06 she became just another background character. Silver was set to be an equal to Sonic and Shadow, but his debut game bombed and after that he was just another part of the ensemble. Shadow doesn't always show up, but someone getting a starring role in
any Sonic game who isn't Sonic himself is extremely lucky.