Whisper?

[Lee-yoshi]

Its been a while since i last played online, but if i remember correctly when your in a battle you whisper by pressing the R-Button until it appears on the bottom of the screen as a chat bubble with the Player Number in it (E.g. P.2). Pressing R will change the chat icon to either 'All' or individual players.

And no u dont need a hardware keyboard to whisper, the on-screen keyboard will do just the same. Obviously a hardware keyboard is more convinient!