Beast Drives are special moves, only available in Beast Form (or Hyper Beast Form) that entails a cutscene and inflicts substantial damage. Most Beast Drives are autonomous (not requiring further player input) with the exception of some such as Uriko 's Beast Drive. Ether it works or not, a character will automatically revert to human form upon the completion of the Beast Drive.
Bloody Roar 2
They first appear in Bloody Roar 2, where each fighters had one Beast Drives, also called Rage Move. In this same installment, Each fighter's commands to use the Beast Drive was revealed when you finished the arcade mode with him.
Bloody Roar 3 / Bloody Roar: Primal Fury
Now, a second Beast Drives for each character is available with even secret third Beast Drives for some fighters as Shenlong or Cronos . The input are also simplified as, now, the player is able to perform this movement by pressing down to left or to right for twice and press the beast button (exception with the secret Beast Drives that have unique inputs).
The Beast Drives can now restore some health as it fills up the Temporary Damage area (Blue meter) in the fighter's Life Gauge.
Finally, with the Hyper Beast Form, the character won't come back in his human form, after the completion of a Beast Drive, until the end of the transformation.
Bloody Roar 4
In Bloody Roar 4, with the new gameplay, the Beast Drives gain the ability to do damage to the opponent's Life meter and Beast meter simultaneously but at the cost of subtract the fighter's own beast meter.
Each fighter has now three Beast Drives, the third ones being, most of the time, an alternative version of an existing one. If a player wants to use the third Beast Drive for his character, he has to unlock it in the Career Mode.
Once unlocked, it's possible to execute the third Beast Drive in any other mode (Arcade, Versus, Training...) by pressing in L1 in the Character Menu when selecting the corresponding fighter. The term "Career" will appear meaning that you can play the fighter with all the abilities he has from the Career Mode New Beast Drive included.