Vocals: Freddie and Shannon doing a duet thingie, that would sound AWESOME!!!
Lead Guitar: Randy Rhoads, Jimi Hendrix, and Dimebag doin a trio Lynyrd Skynyrd thingie.
Rhythm Guitar: Kurt Cobain... if he can actually tune his guitar correctly, and then not smash it up halfway through a song.
Bass: Cliff Burton... or Sid Vicious... (if he can now actually play!)
Drums: John Bonham.
I dont know if everything is clear with the thingie part
Anyway I think this would be it:
Vocals: Freddie
Guitars: Randy Rhoads
Guitars: Steve Clark
Bass: Cliff Burton
Drums: Boham
Piano: John Lennon
Name of the group
Def riot higness of Metallin