The Problem with Darth Sidious

I don't know. I run an all Jedi team for Arena and GW, and he doesn't bother me much, even though he's on almost every squad I fight. I take out the other team's token glass cannon or two, then maybe Lumi to avoid her special attack and healing, and then I take out Sid. I've taken him out in 2 or 3 hits, and sometimes it takes 12+ if he's constantly dodging (which happens). It keeps life interesting. :)

Yoda's tenacity buff, plus putting him as leader, can help counter the healing debuff, and then it's just a matter of time before Sid falls.