You're right: many of TecToy's Brazil-exclusive Master System games were tweaked versions of Game Gear releases. That includes games like Ecco 2, Mortal Kombat 3 and Sonic Blast, but not the aforementioned Street Fighter II which they developed independently.
I think the Master System version of Sonic Spinball came from Sega themselves though. It was sold in Europe as well as Brazil.
I think the Master System version of Sonic Spinball came from Sega themselves though. It was sold in Europe as well as Brazil.