Hi! It is very dependent on the team you are using. The reason why regular kabuto is so heavily used with immortal cancer teams is his ability to do a small amount of dmg to team. The damage he causes actually in essence buffs certain team members like Sailor Sakura and Kimimaro (among the other ninjas that can benefit) as they receive buff everytime they are damaged.

Play around with ninjas at your disposal and also search builds that always helps!

As for Shizune, she is okay when it comes to cancer teams as she does increase the healing for team and also increase her own damage caused by debuffs. However, if you have Original Kabuto that is usually your best bet!

~Jib