I'll make a couple guesses, of course the members pets may not have grown yet but need to start somewhere x3
Some pets may be guessed with more then one user, still many to grow so it is difficult to decide on just one user.
Orchid Sprig

'I used a different tail then I Have for my other two staff pooches'
'Hehe, then I will let you all know that my pup has grown already.'
Last staff pets have had Long, and a Curled tail; So I think either of these c:
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Jadeghost
'Red and Blue, Three and Two"
Right now I'm guessing 'Red and Blue' are the eyes, and the eye we see on this dog does appear blue; Three and Two, could be the pup going from 3 tails to 2 tails, or perhaps getting another 2 tails (so 5 in total)
Probably will be more growths with more then one tail, but for now, I'll stick to this
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RicornThanks Yoyce c: removed
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Captain Kaycee

'Its nothing like I've ever done before'
'I Lingers in the darkness, high up in the night
My eyes will guide me, as they see the light'
I have no idea with the Maleficent Gif, haven't seen the movie or anything, so yeah.
Dark Dog: The speckling kind of reminds me of stars, the dark colours making me think of stars in the night sky
Both: 'My eyes will guide me, as they see the light', I'm taking that as their eyes will open, and that is what is meant by 'see the light'
Rose Dog: 'Its nothing like I've ever done before'
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Yagmur
'its all in the eyes"
Its going to be super obvious which is mine the moment it becomes an adult
Um, see the markings on the body, I can picture them as becoming eyes, like when the pup grows they'll be open eyes on the body and not spots, so 'All in the eyes', a dog with lots of eyes, eyes on the body; which would make it 'Obvious' due to their eye hint.