To unlock Cronos, beat the game twice.
To unlock Fang, defeat Arcade Mode with all available characters, plus Uranus and Kohryu.
Beat the game once to unlock Ganesha.
To unlock Kohryu, beat him in the Arcade Mode, then finish the entire Arcade Mode to unlock him.
To unlock modes, meet the conditions listed below:

Movie Player Option: Beat the game once.

Corn Battle Mode: Beat the game twice.

Kid Mode: Beat the game three times.

Big Kid Mode: Beat the game four times.

Super Buff Mode: Beat the game five times.

Eliminate All Walls Mode: Beat the game six times.

Weaken All Walls Mode: Beat the game seven times.

Break Walls Mode: Beat the game eight times.

Low Speed Mode: Beat the game nine times.

High Speed Mode: Beat the game ten times.

No Blocking Mode: Beat the game eleven times.

Expert Mode: Beat the game twelve times.

Knock Down Battle Mode: Beat the game thirteen times.

Human Mode: Beat the game fourteen times.

Beast Mode: Beat the game fifteen times.

Complete the conditions below to unlock the following stages:

Chaos Lab: Defeat Uranus in Survival Mode.

Evil Lab: Beat the game two times.

Indian Palace: Beat the game once.
To unlock Uranus, defeat him in Round 16 of Survival Mode.