Hi, you can check in here https://pokemondb.net/move/chatter as confuse is chance not always. I think the move go from Gen 4-5 not updated to gen 6
"In Generations 4-5, the player's voice can be recorded and this recording is played back when the move is used. The louder the recording, the more likely Chatter is to cause confusion. The chance of confusion can be 1%, 11% or 31% for a low, medium or high volume respectively."
so chatter never gonna confuse because we cant record any sound, its that right?