i never got it, but Hinotchi is right. you can get Sebritchi the dinosaur as an adult,Pukatchi, the maid looking thing as an adult,or Yattatchi, the wierd tamagotchi as an adult.
I think the tamagotchi character Makiko is rare on the v4 (I THINK) cause on my vpets mailing list my friend's Memetchi turned into a Makiko because it was high in Arts/Talent she had 353 points in Arts/Talent.