Gator Oscillator is based on the Alligator and shows the degree of convergence/divergence of the Balance Lines (Smoothed Moving Averages). The top bar chart is the absolute difference between the values of the blue and the red lines. The bottom bar chart is the absolute difference between the values of the red line and the green line, but with the minus sign, as the bar chart is drawn top-down.

MEDIAN PRICE = (HIGH + LOW) / 2
ALLIGATORS JAW = SMMA (MEDIAN PRICE, 13, 8)
ALLIGATORS TEETH = SMMA (MEDIAN PRICE, 8, 5)
ALLIGATORS LIPS = SMMA (MEDIAN PRICE, 5, 3)
Where:
MEDIAN PRICE  median price;
HIGH  maximum price;
LOW  minimum price;
SMMA (A, B, C)  smoothed moving average. Parameter À  smoothed data, Â  smoothing period, Ñ  shift to future. For example, SMMA (MEDIAN PRICE, 5, 3) means that the smoothed moving average is taken from the median price, while the smoothing period is equal to 5 bars, and the shift is equal to 3 bars;
ALLIGATORS JAW  the blue line;
ALLIGATORS TEETH  the green line;
ALLIGATORS LIPS  the red line.