For crossbones
Just took my claire voyant to r5, and she is amazing. You wont regret it
Quite of the tiers in the road to Cavalier are Villains and some bosses are Robots so Blade and Medusa are your way to go. However I defeated all robots with an R4 Medusa so you may not need to promote her.Be prepared for the 6.1.5 Crossbones... if you have Omega Red is easy... either Iceman could be your best option but the fight is a bit long and based on patience.