I've tested the results, and it works. "Care" involves many variables, such as happy/hungry hearts, training, friendship hearts, and even weight. For example, if you want Uwasatchi (bad care) and you keep your teen tama's hungry/happy hearts at 2/5 each (bad care), but have full training and friendship (excellent care), you'll end up with a different adult than you wanted. You have to take all the variables into account, or you won't be able to accurately affect your tama's growth. Hope I helped!
Here are the different care variables:
Excellent Care: 5/5 hungry hearts, 5/5 happy hearts, light weight, 13/15 to 15/15 training, high friendship
Good Care: 4/5 hungry hearts, 4/5 happy hearts, light-ish weight, 10/15 to 12/15 training, high-ish friendship
Okay Care: 3/5 hungry hearts, 3/5 happy hearts, average weight, 7/15 to 9/15 training, medium friendship
Bad Care: 2/5 hungry hearts, 2/5 happy hearts, heavy-ish weight, 4/15 to 6/15 training, low-ish friendship
Horrible Care: 1/5 hungry hearts, 1/5 happy hearts, heavy weight, 0/15 to 3/15 training, low friendship
The "heart", "weight", and friendship variables I've provided are GUIDELINES. You should try to follow them as much as possible during your tama's growth in order to get your desired evolution. The "training" variables I've provided are NOT guidelines, since training bars are permanent. You must get your tama's training to be within the specified ranges, or it will mess up your tama's growth.