Is the Improved Grab ability different in 3.0? Like, I don't know, maybe no special size restriction, or it working like the 3.5 version's -20 without an actual -20 penalty?
For reference, the question comes from the Gibbering Mouther and its change in the 3.5 MM errata. It seems it doesn't work well before the errata, but it also seems it may actually be the fault of insufficient change (or lack of sufficient change) of the monster during system revision.
I just don't get how a Gibbering Mouther can manage to have a single "opponent grabbed by three or more mouths", or by more than a single mouth at all, for that matter.