May I suggest using Killer Bee instead of Kimimaro with your SN/SSakura team.

run it:
x-x-x
KBee-SN-X
WMC-SSAkura-X

skills for WMC are flexible, I think I'm using 4/4/4/2/2 with Tiger for Arena though you could also do 3/2/4/3/2 for the extra healing. In arena I often just use Killer Bee's mystery on SSakura as she will hit the enemy team without defenses giving 2 stacks of poison and healing twice, Sage Naruto's mystery also stacks pioson on everyone, plus he almost always has a clone in front of him which makes him very hard to take down and since most people don't focus the Sakura she will get tanky fast from normal and AOE attacks and will end up reaching unkillable status while still dishing out lots of damage and poison stacks.

I will admit that not relying on Initiative is a bad idea, you should really work on getting it to a respectable level. I've been able to beat people 5-8k higher than me reliably due to having better Initiative than my opponents allowing me to override their barriers and CC their big play on turn 2.