Who can beat 6.1.5 crossbones

Im thinking of who to find to rank up to r5 so i can beat crossbones

Comments

I did not have r5 but took down crossbones with some units.
Who in your team is poison immune or can shake of poison?

You have asked a question, so, the least you could do is provide us enough information of who you have, so that we could help you pick.