Sonic helps save Knuckles by lifting a pillar up off his midsection.
We can find out the width of the pillar by comparing Sonic's height to one of the identical pillars crafted by the architects in the temple.
Sonic height = 1.0497 meters = 261.84 pixels
Pillar width = 375.98 px = (375.98/261.84) * 1.0497 = 1.50728004 meters
Treating the shape as holding 2 truncated cones, a cylinder, and a cylinder diagonally sliced in half
Light Red line = 1.50728004 meters = 345.9 px
Cyan Line = 674.87 px = (674.87/345.9) * 1.50728004 = 2.94078659 meters
Cylinder volume = Volume = pi * (r^2) * (h) = pi * ((1.50728004/2)^2) * 2.94078659 = 5.24736515 m^3
Green Line = 209.65 px = (209.65/345.9) * 1.50728004 = 0.913562476 meters
Half cylinder volume = Volume = (pi * (r^2) * (h))/2 = (pi * ((1.50728004/2)^2) * 0.913562476)/2 = 0.815053346 m^3
Yellow Line = 134.53 px = (134.53/345.9) * 1.50728004 = 0.586222561 meters
Orange Line = 464.78 px = (464.78/345.9) * 1.50728004 = 2.02530679 meters
Truncated cone 1 volume = Volume = (1/3)*pi*((r1^2)+(r1*r2)+(r2^2))*h = (1/3)*pi*(((2.02530679/2)^2)+((2.02530679/2)*((1.50728004/2))+((1.50728004/2)^2)) * 0.586222561 = 1.89104684 m^3
Lime Green Line = 559.31 px = (559.31/345.9) * 1.50728004 = 2.43722694 meters
Dark Red Line = 268.28 px = (268.28/345.9) * 1.50728004 = 1.16904622 meters
Truncated cone 2 volume = Volume = (1/3)*pi*((r1^2)+(r1*r2)+(r2^2))*h = (1/3)*pi*(((2.43722694/2)^2)+((2.43722694/2)*((2.02530679/2))+((2.02530679/2)^2)) * 1.16904622 = 4.32123837 m^3
Total pillar volume = 5.24736515 + 0.815053346 + 1.89104684 + 4.32123837 = 12.2747037 m^3
Going to assume granite density or 2700 kg / m^3; Stone pillar is = 12.2747037 * 2700 = 33,141.7 kilograms
Applying Archimedes Principle; the water displaced is = (1000 kg / m^3) * 12.2747037 = 12,274.7037 kilograms
Therefore, the apparent weight is = 33,141.7 - 12,274.7037 = 20,866.9963 kg
Both of them contributed pretty evenly so they should scale to about half each; so let's just divide by 2 and call it a day.
Knuckles/Sonic solo lifting strength = 20866.9963 / 2 = 10,433.4981 kg
or Class 25