Kazuha Melt Ganyu
Though each individial Charged Attack deals a lot of damage, Melt Ganyu with Kazuha suffers from several major issues. The setup is difficult, though this can be overcome with practice.
It has extremely high Energy requirements, requiring an Energy Recharge Sands along with Energy weapons on both Kazuha and Bennett.
While it is possible to do 5 Charged Attacks, most people will only be able to do 4. In the event you can only do 4, you should attempt to do a second Benentt E in order to recuperate damage with Energy. This requires him to catch the last ticks of his Burst to reduce his Skill cooldown. This isn't too hard to do with a bit of practice though.
The final, and possibly biggest problem, is in single-target, Kazuha's Pyro application is unreliable. He applies just enough Pyro to Melt all of Ganyu's Charged Attacks, but the addition of Zhongli's Pillar or Ganyu's E can nullify this. However, in AoE, this does get better with additional Pyro Swirls, but Melt Ganyu is generally a single-target orientated team.
Zhongli hE (Break Pillar) (dash) Ganyu E CA Kazuha tEP Bennett Q (clear Cryo) (Ganyu E explodes reapplying Cryo) Kazuha Q (Swirl Cryo) Ganyu 5CA Kazuha tEP Bennett N1 E