The Pokémon Tower Defense Avatar chat was added on PTD1. Its current version is v1.9.
PTD Avatar chat was added in v4.6.1. You use the same email and password that you would use to log in to the game. It has 1 huge flaw however...
SPAMMERS! Every one hates them and they are really annoying. However, the ignore function added in v4.8.1 can be used to prevent spammers. It can be used by typing /ignore and then the spammer's name.
Sam's name on the avatar chats is samO. Sometimes he disquises himself as a random player.
Every time a new avatar is added, Avatar Chat needs to be updated. Avatar Chat's current version is v1.9. Use this link (Bad news: the link does not work because avatar chat does not exists anymore. It has been deleted for three years) to go to the avatar chat.
The avatar chat.