This is correcting a calc already out there made by Monkey Dunno. Scales to all second stage Pokemon. Feat starts at around 17:48 in this clip.
The whirlpool is hollow inside, so we need to substract the hollow part of the overall ellipsoid. Using this equation (V = ((2/3) *pi * (R)^3) - ((2/3) * pi * (r)^3)): 2/3 * pi * (973.74/219.55 * 74.433152713 meters)^3 - [2/3 * pi * (910.43/219.55 * 74.433152713 meters)^3] is equal to 75350573.95 - 61588157.62 = 13762416.33 m^3. As the density of water is 1000kg/m^3, the mass of the whirlpool is 13762416330 kg.
The equation of the RKE is = (1/2) * Inertia of the object in question * (angular velocity)^2, where the inertia of a hollow hemisphere is found by (2/3) * Mass * (Radius of the whole sphere)^2, and the angular velocity is found by W = radians/time.
Inertia: 2/3 * 13762416330 * (330.1231525)^2 = 9.998973101 x 10^14 kg. Angular velocity: The whirlpool took around 3 seconds to rotate 180 degrees, so the angular velocity is pi/3. Rotational kinetic energy = 0.5 * 9.998973101 x 10^14 * (pi/3)^2 = 5.482550496 x 10^14 J. This is low-end Large Town level.
Since I'm at it, might as well recalc Gible's boulder feat.
Volume = 4/3 * π * 2.891875 * 2.3078125 * 2.3078125 = 64.51625782 m^3 Density of rock is 2700 kg/m^3, so the rock has a mass of 174193.8961 kg, which is Class K.
Many thanks to AlexSolo for helping me out with this calc.