I’d keep the six and fix the unfinished sets first. Milotic has no item in the screenshot; Leftovers fits Scald / Icy Wind / Life Dew / Protect and isn’t taken elsewhere. Rillaboom also has a neutral nature—Adamant makes sense for that 32 Attack investment unless you need a specific Speed benchmark.
Charizard is the bigger decision: it has 32 HP / 2 Def / 32 Speed and no Sp. Atk investment. That can be deliberate, but if its job is immediate burst damage, I’d test moving some bulk into Sp. Atk before changing a Pokémon. Your sun also weakens Milotic’s Scald, so those two are not always your best attacking pair.
With Kleavor, don’t feel obliged to click Tailwind turn one. Stone Axe pressure beside Fake Out can be better when you already move first; Tailwind matters when it lets Garchomp or Charizard attack before a specific threat. Stealth Rock only damages switch-ins, so avoid counting that chip against the opponent’s starting lead. Those are the first things I’d test before rebuilding.