regardless of the boat choice, what skills do the sailors need for the Olympic multihulls?

General sailing (any boat, mono or multi)
Buoy racing (any boat)
High-performance sailing (dingy, multi, skiff)
Multihull sailing (Formula multis)
Trapeeze work (skiff, multi)
Spinnaker work (skiff, multi)

so maybe picking the existing, bigger groups might help:

Basic sailing - Opti, Wave, O'pen
Course racing - 420, Wave, Dragoon, H-16, Formula multis, Skiffs
High-performace sailing - skiffs, Multis
Trapeeze sailing - 420, Skiff, Multis
Spinnaker sailing - Skiff, Multis (420 would be too slow)