The Union Room...Accessible everywhere in Kanto. This room will allow anyone who has a wireless adaptor and is in the wireless room and within a certain distance of you to be in the room with you
You can then go up to any trainer and start a conversation or challenge them to a battle and many other things
However you are also able to go into a Chatroom which has a small keyboard so you can chat if say you are in different buildings. This Chatroom may rival our own #SPP
Battling is also Possible here and it is noted by there being a wire icon in the top right

 
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