I don't think skill point's make a big differnece in what they change into but their care level might , check V6 growth charts on google, hope i could help
Care level doesn't matter much either. I cared very well for Steve (G1 on my Music Star) he was Kuchitamatchi and I cared just the same for Jayjay (my current tama) and he was a Kuribotchi. I think it's just random whichever one it becomes.
I don't believe care is a big factor either.I also take good care of my tamagotchi and he ends up become a Kutchitamatchi.Some people have gotten Kuribotchi from poor care.