My V3 and my V4 has suffered problems with the friends list before. My friend's V1 has, too.
V1 has a tendancy to return to regular play shortly after showing the 'low battery' sign. My friend and I tried to connect after the sign had shown up and disappeared, and we began to notice that every time we did this, the friends list would change. In the end he had about 15 blank entries on the friends list, all with Japanese names. Some of them showed a character for a split second before becoming blank again. Surprisingly, these characters were usually debug-only characters.
On my V4, my friend and I once tried connecting (I believe I was connecting with his V1); his Tamagotchi was called ADDY, but the sunlight must have interfered with the connection, meaning that it shoes as ADbY on my friends list (yes, there is a small 'B').
On my V3, however, no glitches were caused through connection. On place 50 of my friends list (even if I have less than 49 friends), there is an entry of a Japanese Tamagotchi. Neither do I remember which Tamagotchi it was, nor do I remember the Japanese name. The Tamagotchi seems to disappear every time the battery is changed, but soon returns, only with a different (but still Japanese) name.
