Hi there!
Cute pets!
As far as value goes, I would expect each pet to go no higher than $4 on eBay. Every pet that is, except for the purple/gray spaniel on the far right in the first picture, most of the horses, and the white cat with blue eyes near the middle in the 7th picture. The spaniel often goes over $10 in an auction, as the spaniels are in such high demand. It's difficult to make an estimate for the horses, but they sometimes sell for about $6 a piece on average. I've seen the white cat go just above $10 as well. Your friend may want to use nail polish remover to get the black marks off if they are paint or nail polish.
And I just noticed that Great Dane in the back of the first picture- I can't excatly tell which one it is, but the Great Danes are sure to go above $10 in an auction.
Here are the numbers of each of the pets by picture. If your friend wants to sell them, she can look these numbers up on eBay and see how much each one tends to cost:
Picture 1 (back row to front, left to right): LPS fakie, LPS fakie, LPS fakie, #466 (?), #875, Great Dane (?), #335, Sheepdog (?), #1077, Sheepdog (?), #255, #672, #509, #591, #561, #789
Picture 2: #517, #516, #654, Special Edition Grooviest Owl, #496, #496, #676, #761 (?), #825, #635
Picture 3 (horses): #338, #578, #840, #523, #578 (if it has green eyes, then #584), #337
Picture 4: #510, #157, #624, #625, #633, #589 (?), #633, #589 (?)
Picture 5: #677, #1822, #671, #600 (?), #590
Picture 6: #513, fish (? may be customized), #823 (?), #1946 (?), #503, #651, #111, #637, #913 (?)
Picture 7: Magic Motion cat from Biggest Littlest Pet Shop set, #64, Magic Motion cat from Get Better Center set, LPS fakie, LPS fakie, LPS fakie
So yup, that is for your friend's reference if she would like to consider selling on eBay.
The animals in the other pictures are Puppy in my Pocket, Polly Pocket, Animal Planet, Barbie, etc. The LPS accessories sell well on eBay in lots if the bidding starts low. And, if the bidding starts low for any of these pets, the seller will get better results.
Hope this helps you and your friend!