I took a quick look on Internet. It turns out that Tamagotchi devices use an infrared port not a wireless (radio) transmitter to connect to other Tamagotchi devices. So the ban on transmitters (such as cell phones, WiFi, and 2-way pagers) during flight does not apply.
That still raises question about the ban on any personal electronic devices turned on during takeoff/ascent and approach/landing.
Keep in mind that checked luggage will be on the same aircraft just a few feet below the passenger compartment. If the airline doesn't allow electronic devices to be on in the passenger compartment, they shouldn't be on in the luggage compartment either.
Whether Tamagotchi devices are banned (because they can't be turned off) and whether they actually create any sort interference with the cockpit (highly unlikely) are two different issues.
I suppose leaving the Tamagotchi at home is not an option?[/QUOTe
How about just taking the batteries out of it (if that is it's power source), or, will it virutally die?