I have some Midnight Beach Bratzillaz, I tried a MH and an EAH dress on one for you. Unfortunately both of them are too small. The MH dress (for reference, I tried FdC Rochelle's dress from the playset) almost didn't even get past her hip, and once I managed to pull it up the velcro didn't even get close to be close-able. The EAH dress (it was a Sig Apple dress) did not get stuck at the hip and I was able to close a very small part of the very bottom of the velcro. From the front it looked good, but there's a huge gap in back.
I'm not too knowledgeable about Bratz, but I think regular Bratz dolls are smaller and thinner than the Bratzillaz, so I wouldn't be surprised if Bratz clothes wouldn't fit either. I know some regular Bratz clothes fit Monster High relatively well, which also hints at that they are likely too small for Bratzillaz.
Later Bratz lines included some taller dolls, those may probably be closer in proportions to the Bratzillaz, but this is just a guess, I don't know what body proportions those dolls had.