You usually get a Kuribotchi toddler through good care.
I don't think anyone has tested a proven method to get Kuribotchi because it is one of the four toddlers you will get as your V4.5 tama evolves and is only with you for 24hrs.
Try to make sure that you keep the Happy and Hungry hearts full and to play plenty of games with it.
If you have already managed to get a Kuribotchi before then it would be a good idea to try to remember how you cared for your tama last time! If you can't remember, perhaps it would be an idea to keep notes on care - feeding, games, etc. so that if you get a Kuribotchi again you can use the notes you took before as a guide for the next time.
Good Luck!
I've included links to a couple of growth charts in case they are useful to you:
http://www.tamatalk....harts-complete/http://tama-zone.com...showtopic=15082