The healing immunity the B2 does, prevents any protection recovery and because Palpatine is gaining a ton of TM he will feed the B2 a ton of TM (30% when he counters and 5% everytime he's attacked) and as a result the B2 will outspeed your TM removal chars.
Going to be tough timing Ewok Elders cleanse with all the turns Palpatine keeps getting, so you can end up with STH dying because Ewok Elder didn't get to his turn. Before you get the chance to revive STH, Palpatine will likely get wrecked.
To be fair, Baze is F2P and you can get ~100 baze shards a week (buying from the Guild Event store). Add Chirrut, Teebo and TFP with them and you can do up to 5M damage roughly.
I've been using Teebo, CLS, DN and Chaze doing 3.6M damage but Teebo died when the B2 had 7 turns left so I had to go all out on the boss (feeding him with TM so I don't miss P4). Tried Teebo, CLS, Jyn and Chaze before - found them to be much more consistent with removing TM. I'm confident you can solo it with Chaze but I've never had the chance to do it because of guild reasons.
Even if you pull a solo out with them, you have to be very lucky with not being resisted.