In reply to Carolyn:
As far as I was aware, (i.e. I was told, whilst I was a probationer chasing a lad from Brecon team up the side of a hill/mountain/earthy protrusion in wales last October on my first multi-team call out) there is a certain set of skills, set out by MREW that all it's full members should have, ropework, belays and anchors, water (bank side) rescue, navigation, comms/airwave, RAF SAR familiarisation, BLS and defib theory etc.
These "core skills" are backed up my more specific skills done as "opt in" training like Swift water rescue, Crag rescue (e.g. Rigging for rescue/Oldham method) and the Cas Care certificate.
I'm pretty sure that's what I've been told my our training officer too. Certainly the "Core skills" training sessions are mandatory, and there are often MREW syllabuses flashed up on the projector. The more recent jobs involving other teams, there's always been the assumption that I knew what to do when given a task, so I have no reason to think this isn't true.