27cm Obitsu's are just a bit thinner than barbie. Anything that fits Barbie will fit, some brats clothes may stretch to fit, etc. Most fashion dolls the same height will work.
And my scene heads will fit just fine. You can hybridize obitsu bodies with just about anything, matching skin tones is the only real issue. You're going to need a normal skin obitsu, not a white skin, if you want any chance of matching it with barbie or my scene. Your best bet would be to take an obitsu to the thrift store with you, and try matching the skin tone side by side. There I'm sure there's a myscene girl who's skin is close enough. :3