Sonic And FriendsFile :

1. Zbrush (ztl)
2. Blende(Blend)
3. FBX

To reduce the vertex of characters like sonic, tails, and also knuckles open the zbrush ztl file.From the character file, all subdivisions are max lev 4.

Sonic the Hedgehog is the protagonist of the Sonic the Hedgehog video game series published by Sega, and appears in numerous spin-off comics, animations, and other media. Sonic is an anthropomorphic blue hedgehog who can run at supersonic speeds and curl into a ball, primarily to attack enemies. In most games, Sonic must race through levels, collecting power-up rings and avoiding obstacles and enemies.

Programmer Yuji Naka and artist Naoto Ohshima are generally credited with creating Sonic. Most of the games are developed by Sonic Team. The original Sonic the Hedgehog (1991) was released to provide Sega with a mascot to rival Nintendo's flagship character Mario.Sonic was redesigned by Yuji Uekawa for Sonic Adventure (1998), with a more mature look designed to appeal to older players.(Wikipedia)