Several hacks by Kencho. The game is Return of Double Dragon. 

The Dragon Power Meter now increases 33% faster.
Billy and Jimmy’s basic attacks (just pressing punch or kick) are now two frames faster for better responsiveness.
Blocking is no longer timed. It is done just by holding the blocking button, in the fashion of other games like Mortal Kombat or Soul Calibur.
If the defense button is held when another move is finished, will start blocking immediately. The blocking condition is not the button press, but the button hold.
Blocking while holding a weapon will now drop it and enter the “defensive” mode.
The R button is now used for blocking, instead of increasing the Dragon Power Meter.