Nope, ARBs aren't ring-bound unless they're the RB.
Here's an idea.
Gimli RB
Start Bilbo and Sam
Boromir and Isildur come out with some
Armor of the White City and artifacts for Isildur, making them the beatsticks.
Gimli draws cards, Bilbo does Tale thingy with
Hardy Garrison racket thrown in to wound all the minions to death. Sam takes care of any left over minions.
DOUBLE!
Perhaps? This is the best way, I think, to have each companion actually be useful and not just thrown in b/c he's an ARB.