Are the character setups used in Stealth capable of being made in ZBrush?

Would I be able to use ZBrush along with retopology programs to create character setups used in the Stealth tutorial series? How can this be done exactly and would I be able to do all the possibilities done within the series, especially in the Animator section.

Also, how were the characters made in the series? Or at least what are some strong possibilities?