If you take care of your pet the same every time, she/he will basically turn out the same. try experminting.
Only answer the tama's call when it beeps twice.
Play the games that you didn't play as much last time more.
Feed it only apples and tarts as snacks, or only ice cream and pudding as snacks.
Just play it differently. That's actually one of my favorite parts of tamagotchis- watching it grow into different charcatars depending on how i take care of them.
Sorry, I'm not an expert on how to get different charcatars, so I can't tell you much about getting Kutchipatchi, but I think he needs to be a bit over-weight and plays games a lot.
Hope this helps,
D.C.