Snake and any of the Starfox characters can perform special taunts on specific stages. These will start a dialog with other characters on the stage.
Snake:
When you are on the Shadow Moses Island stage with Snake, tap the down taunt button extremely quickly to start the dialog. You have to do this in just a split second, so it's best to just brush the button. This will start radio communications with his teammates who will analyze the other characters and give some interesting information about them. You will probably need to make sure the other teammates are willing to leave you alone while this happens as you can still be killed during communication.
Fox or Falco:
These taunts can be performed on either Lylat Cruise or the Melee Corneria stage. Do the same brush down taunt and the other Fox team members will start talking to you as they fly past. You can hear commentary from Peppy, Slippy, Wolf, Leon, Panther, Krystal, Fox, or Falco.
Every man dies, but few truly live. Live your life to its fullest, every day as if it were your last.