@Alexander Thaut
I mean, me and others have recommended Serval and Dan Heng. This sounds rude (or my entire post), take it or leave it.
1) Put it this way, overworld enemies, all mechanical units have
lightning weakness. Dan Heng is sufficient as single target DPS for some enemies in later part of Luofu, like this pos. Houhou herself should be auto attacking and help Dan Heng as well.
2) Qingque herself without eidolons can be screwed with rng horribly and can costs way too much skillpoints for bad rng. Therefore, not as recommended. When people talk about Qingque, she's considered at least Eidolon 4. Use her if you are that confident in E0. Also, not like you are really need to maxing Disaster Swarm simulated universe at highest level now.
Even considering fighting Cocolia, having like a fire units (Trailblazer, Asta) and Serval can do it.
Do you know why nobody recommends Arlan? Can he does good damage? Yes. However, being weirdo attack that costs health without having any defensive bonus for himself. He relies a dedicated shielder like March 7th or Gepard (whom you don't have) to cover for. Why does he need a dedicated shielder? Because all multiple phases bosses have AOE attacks, and then enemies with CC.
Arlan isn't like Clara (no defensse up bonus with ult) or Blade with high health pool and self heal.
3) I'm not sure how you feel, but last time I played. There are way more dangerous enemies immune or having resist against fire and ice effect more than lightning and wind. Not sure how you feel about Luofu hounds or that wind centaur.
4) My recommendation is based on your account level. It's stil very new and
you are spending way too many resource on too many characters. Nobody knows if you are fully F2P or at least have battlepass to cover for money & characters level up. Pretty much the majority of Trailblazer power are used for farming mats and relics instead. You have no idea how expensive/costly it is to getting from 60 to 70, then 70 to 80. Then pray rng gods for at least okayish appropriate relic stats. Because like around levels 70-80, good relics carry like 70-80% of a character strength.
Ignore memory of chaos. Don't bother about it at this stage.
Another thing is that, 5* characters and lightcones require more resource than 4* ones. If you are already have Himiko at that level then
I'm impressed with your dedication. Most or half of her damage comes from her following up attack, which requires you to have break enemy weakness 3 times (anyone on your team can do it). In boss fight, there isn't that much trash mobs, you are effectively doing much less damage. TL;DR: she is pretty meh for a 5* unit, along with Yanqing.
5) Sushang is decent, if you want her to help you against Gepard boss, Belobog shield lieutanant, Kafka and Bronya.
It’s so wierd to me that the Fatui are the only enemies with guns.
I mean, don't think too much about Genshin techonology advancement wise.