I noticed that the code posted before didn't change the font in battle messages, so copy this:
# Adding option to reset message window in maps & battles
@message_window = Window_Message.new
@message_window = Window_BattleMessage.new
# Adding code callable by events:
ORIGINAL_FONT = Font.default_name
# change_font() let you change the font by passing font name as usual. Ex: change_font("Arial Narrow") or change_font(["Arial Narrow","Tahoma"])
Font.default_name = font # set the font
$scene.renew_message if $scene.is_a?(Scene_Map) || $scene.is_a?(Scene_Battle) # reset the message window
# restore_font let you restore the original font once you changed it by change_font()
change_font ORIGINAL_FONT # calls change_font by passing the original font
Well, I commented out everything, but you really don't need to know what the script does in order to get it working (:
I also edited the message above with this code.
For how to use it, I hope the event list image speaks more than thousand words ^^
You have just to use the "Call script" command, third page of the event commands, the only one in the "Script" group.
If with doing this, it won't work: are you using other messages script? If so, what script?