What does it depend on, how fast pets are fed/eligble in battle once put into the resort? I just did 40 battles and the T11 pet still did not show up and needed to be handfed, and the other 3 pets (very low levels) appeared in no time.

Also, sometimes I will get the check out notification and the pet in question is still above zero for the whole day, then again they drop out within a few hours.

I think they're fed on the hour, so if you put them in at 3:05, they won't be fed until 4:00

oh, o.k., I didn't check the time I put them in, probably will next time - providing I remember :-) May well be that, even though put in in 2 groups, they all got fed at the same time.

And they are getting fed to full pretty fast now. (while depletion periods, as mentioned, vary) Quite honestly, I also have been wondering for some time, whether the feeding level actually still has any impact on their fighting skills.

feeding level doesn't affect fighting skills. You pet only needs to be not hungry.

but it used to... a fully fed pet hit harder than one at 5 or 3. What sense would the feeding stages make otherwise.

The feeding stages also determine how much food you can feed to your pet at once, if you're going for the gourmand achievement or something. It wouldn't make sense to have your pet's stomach be a bottomless pit, so there needs to be some sort of limit to how many items you can feed them before they get full. So they decided on 10 stages I guess, and then you have to wait for them to get hungry again if you want to feed them more.

The hunger level has nothing to do with how well they battle, at least not anymore if it ever used to.

ah, sure, my bad, forgot about that!

Subeta has many relict features of other petsites that seemed important at the time. I think the original virtual pet Tomogotchi feeding changed how they reacted and they could starve to death if you didnt' feed them or run away if you fed them yuckies or something? Anyways unlike some petsites pets here always eat whatever you give them (if they're hungry) and their response is canned and entirely random and doesn't seem to affect their mood in any way.

When battling stats were a step-function instead of a smooth curve, how much damage pets could do was calculated out exactly and even today with the smooth asymptotic curve we've got some geometric formulae approximations and they are very finely calibrated. Food/strength ratios are not accounted for in them at all and they'd go wonky if they did count for something.

I think Neopets could have some problems if you fed them until they were bloated, so you had to keep that balance between hungry and overfed? I don't remember anything like that on Subeta though, unless maybe it was before my time.