tamaw/pants has a good point. If they claim to be tamagotchis, but aren't from Bandai, they are most definatly fake. If they don't claim to be tamagotchis but are a different new kind of virtual pet, that does not make them "fake tamagotchis". True, they aren't tamagotchis. But they aren't meant to be. They are meant to be similar to tamagotchis, but they as long as they say that they aren't accual tamagotchis, then they aren't fake tamagotchis.
Hope I helped and wasn't too confusing.