Here a few counters,
Zader counters the HoT with DoT, has unavoidable Cull with damage multiplier for debuffs.
DNihilus counters buffs by dispelling them, and annihilates someone after 3-4 turns.
Boba Fett counters buffs/debuffs stacks with Execute. Bounty Hunter Resolve allows targeting outside taunts.
Together in a team, provide 3 types of insta-kill.
As for individual toons: Zooku, Zkylo and Zavage would be able to beat Chirrut or Baze 1-on-1.
You don't have any of the counter toons above? Oh NO! Well how about spending the next 2 months farming and building them like I did to counter the Rex + Chaze teams. I did this 3 months ago and haven't spent a cent on swgoh.
Regards,