I think a pokémon that can make use of otherwise unused moves or moves that aren't used to their full potential would be an interesting concept. This would include low-accuracy moves, recharge moves, low power moves, etc. This is similar to the Special No Guard concept, but more open; we could give it No Guard and a movepool containing Purgatory and the crew, or make an ability that makes recharge moves viable, with relevant movepool, or give it Technician and a unique Technician movepool; there are many paths to be explored, whereas the NG concept is rather restrictive.