When I rigged My mesh I have this ..

[dima Chun]

:matte-motes-frown: 

 

[Lukeh Ghost]

That's 1 hung avatar!

 

But it could be down to the weight paint

[Braydon Randt]

definately ,  go into weight paint .  and check  the strenth  of the painting on that leg  in comparison  to the skeleton ,  as its not quite right,  however....  the SL  av  has crap crotch vertex groups anyway 

 

Bray

[Gaia Clary]

This might help:

 

• Machinimatrix: Mesh rigging
• Machinimatrix: Mesh Weighting

These are 2 brand new tutorials which i have uploaded an hour ago. The secnd tutorial might be a bit rough on first view. But maybe it is still useful

[Yabusaka Loon]

I think its also important to know that, especially for crotch and shoulder parts, there are pretty much no way to rig it perfect with very simple skeleton system of SL.

To my knowledge, in many games, charactor body and outfits were modeled all together and they basically swap models whenever changing the outfits.

For prerendered movie and other 3D movie, the clothing were often modeled on top of body but still they usually hide or delete body inside the outfits. Otherwise they use more complecate rigging system with deformers, extra bones, constrains, morphing, etc.

I'm sure the better wight painting will improve the bad deformation as in first picture but I think it cannot prevent the skin stick out of clothing in all the poses.

Also, your clothing model seems quite high-poly. Its usually easier to make the clothing follow the body if the number of poly and geometry is closer to the body model.