Mametchi, Kuchipatchi and Gozarutchi are all Universal characters on the v4.5. Gozarutchi is the "absolute worst" male character you can get, followed by Kuchipatchi, then Mametchi.
To get the "best" Universal character (Mametchi/Mimitchi) you can try what I did on my v4 for Pyonkotchi. I looked after it very well, but instead of playing games when it was unhappy, I fed snacks. I didn't play games at all or feed any foods that would raise skill points. I still disciplined and fed my Tamagotchi every time it dropped a heart and ended up with Pyonkotchi. Doing this with a male Tamagotchi on a v4.5 should give you a Mametchi.
For Gozarutchi, you should give the worst care possible. I think you might be able to get one if you let it get sick from extreme hunger/unhappiness about 2 or 3 times. Maybe even 1. Don't let it get this sick too many times though, or your Tamagotchi may depart. (I think I remember reading somewhere that the maximum might be 4, on the 5th time it dies, though that may have been for a different version.) I haven't tried this for myself.
Kuchipatchi would probably be somewhere in between. Maybe let it beep at you for food/happiness (but not get sick) about once or twice. I haven't tried this for myself, though.
