You can solo strong approach easy, but you'll probably need clones (lvl 55) or really high power to do it. I used this setup to do it:
Sasuke Fire Main x
Kabuto x x
Sakura x x

I had all 3* characters though.

My talents were the Flame Dragon Jutsu, Fireball Jutsu, Genjutsu MIrror Return, and Oboro Clones
Summon: Chameleon
Note: You can't auto battle this or you'll die.
Round 1: Call out Kabuto's clones first and save Sasuke's lighting attack for Round 2
Round 2: Heal if Sasuke's lightning attack isn't ready or if you don't have the Flame Dragon Jutsu ready.
The minute after Shizune heals herself, hit her with everything you've got and hopefully your combo's long enough to beat her.
Round 3: Kill Karin first, and then focus on Hanzo, hopefully you've healed enough to survive Hanzo's mystery.

Note: I soloed it twice but my power was around 11.5K