The following codes require a Dreamcast keyboard. During the game you have to press ~ to arrive at the console command screen. After that, enter one of the following commands to activate the corresponding effect:

Granted Wish - Cheat Code

Clear console line /clear
Display console commnands /help
Send message to indicated player /say[1-4]
Send message to player that is attacking you /tell_attacker
Enable third person view /cg_thirdperson 1
Disable third person view /cg_thirdperson 0
Display player list /who
Send message to all players /say
Send message to player that is targeted /tell_target
Send message to your team in team modes /say_team