[Spoon]

Anything based in the MOTU Origins scale is 5.5 inch, same as vintage.

I think some of the confusion might be coming from the fact that the Cartoon Collection figures stand taller. This is because they have longer torsos and their thighs and knees have been redone and can stand up straighter. Here's a comparison shot.

The second issue is that although figures are stated to be in a certain scale, they unfortunately sometimes skew to one side or the other. S.H. Figuarts are closer to true 1/12 scale (6 inch) versus something a little larger but also 1/12 scale like Marvel Legends or Classified. Let's not even talk about Storm Collectibles "1/12"

So the Cartoon Collection Figures might work with true 1/12 6 inch Scale figures but are a little undersized for something that's closer to 6.25+ inch Scale. Currently your best bet would be custom Joes on smaller 1/12 scale bodies. Maybe Sigma 6 figures would work, but they're stylized and I'm unsure on the scale.