It depends on whether rare is determined of how much it costs to buy when people sell it or how often they show up or even how many are made.
I think one of the rarest would be the Eco tamagotchi Kuchipatchi entama it was a campaign that was based from an Eco panda and a japanese green tea beverage I'm not sure if it's that rare but I've only seen them for sale once or twice and they wouldn't of made many
Also isn't the beta osu mesu supposed to be quite rare? As it was kinda banned and they are pretty hard to get
The Conan Id like everyone's saying is probably one of the most rare though..
If your talking all tamagotchi devices probably the rarest of them all would be the tamagotchi stations from id to p's as no one owns one and they are available to stores only. And also the tamagotchi restaurant.
thats some really great points ^.^ i have never seen the eco shell before
when i mentioned this topic i had meant along the lines as to how many were made in total for rarity, cause i know some of the prices can be bet if waiting long enough, just take my santaclautchi for example i just purchased the nib green shell design for $93 total... haha the prices can be bartered with a little. i will be eventually looking for the devilgotchi but im in no hurry ^.^ i wanted to know what kinds of tamagotchi's that are out there that im obviously missing<3 thats why i made this topic ^.^