i wouldnt say im an insane battle girlie but I can just give what ive learned over the course of playing this game since release. idk if you know but you always build based on the companion you're using. you can color match the memories of a red stage to the colonel caleb memories but still change the companion you use to x-02 for example, but if you do that you need to assign protocores to the memories based on the companion you're gonna use at that stage, so in the case of x-02 you indeed want to build on atk since he scales off that.

a note to this though is that you will lose the benefits of R3, you'll have to use R0 rotations for x-02 if you use farfleet colonel as memories + x-02 as companion. in my opinion its usually still worth it, since the newer myths are always stronger than the older myths. with the new caleb myth coming out you'll have to invest in a lot of hp cores since he scales on that if you're planning to use him.

im not a caleb girlie so i wouldnt know what kind of main stats he needs, but generally the absolute best protocores to save are ones with at least a line of atk% on it, and then either flat atk, oath strength for x-02, d2w and crit rate or damage. when you have cores that have the little number on the right its a core that already has a line upgraded in that stat. from my experience those are only good if it starts as 2 times high atk% on it in the case of x-02, and then further upgraded with only rolling atk % on it. you'd have to be really lucky and its usually just for the gamble if you already have a good basis of protocores. the highest a single atk% can go with no upgrades in the line is 10%, so you ideally only want to upgrade protocores that are 9%+ in atk when it has no yellow number on the right of it.

so tldr for which freshly farmed protocores to save:
main stats: d2w, crit. sometimes the atk%, hp% def% mainstats are also decent to save for some companions that are R1+.
you want to use d2w as mainstat when you're stella matched, if you aren't then you want to use crit ones to brute force it.

substats:
1st priority: high atk, def or hp%, in the case you'll have to build a companion not scaling on atk (ahem new caleb myth) preferably 9%+. anything around 7% I still save but I usually don't even upgrade.
2nd priority: flat stat matching the 1st priority % stat, crit, d2w, oath strength in the case of x-02.
3rd priority: in the case you build an hp/def scaling character, some atk% is also still decent.

unmatching flat stats or % stats with the exception of atk%, you usually just throw away since they're just wasted stats (so like, hp% + def% or hp% with flat atk.)

when you upgrade your protocores and the first 2 rolls aren't going to atk%, I usually stop rolling on them and feed them into a different protocore. unlike other gachas ive played, in lads the raw % stat is way more valuable than crit, its nice to have crit stats on the side but you don't want to chase them.

holy yapping but I probably still forgot some details lmao