Overall your team members is quite solid, and I don’t think you have to change members, but I’ll give some suggestions for the sets. Are your mons EV trained btw?
Whimsicott
Nature Power (pairs with prankster very well, swap moves depending on the fight)
Rotom
Hydro Pump > Water Pledge (increase damage output, unless you wanna change fields)
Volt switch > Thunderbolt (for pivoting, but thunderbolt can be used for dmg)
Will-o-wisp is a great move too, cripples the enemy heavily. Swap depending on fights.
Charizard
Heat Wave > Flamethrower (HW is generally better for doubles, useable in singles as well)
Roost can be used for longevity but it depends.
Aegislash
Shadow Sneak > Sacred Sword (STAB priority is better, and zard already haves fighting coverage)
Additionally, I will build Aegislash to be a Specially Defensive sweeper (252HP, 252SpD), because King’s Shield already lowers the enemy’s attack stat. Alternate between Kings shield and SD to maximise leftovers recovery, and when you’re at +6ATK you’re good to go.
Kommo and Krookodile’s sets are good IMO.
When you wanna change sets, you can go to the Moveset Saver at the nightclub (the one beside arclight), he’ll save your mon’s current set at no cost, so when you’re experimenting you can just revert them back.
If you’re using toxic stall, you can teach your mons protect as well, so you can stall for another round.
Also, in postgame there’s a lot of new world fields, try using the magical seed and you might get unexpected results. (Seed + power trip Krookodile?)
Thats my suggestions, just take anything you want~ and have fun with the game xD