When someone would earn a badge, a chat message will appear for everyone saying [player] earned [badge name] I know I would use setcore, chatmakesystemmessage But what else should I do to make it appear on everyone's chat, not only for the person who earned the badge?
First of all, when the badge is given you will need to fire this from a server script. Edit as you wish, I suggest putting it into a function, so you can see who the player was.
bc = BrickColor.new("New Yeller") game.StarterGui:SetCore("ChatMakeSystemMessage", { Text = "Player has earned a badge."; Font = Enum.Font.Cartoon; Color = bc.Color; FontSize = Enum.FontSize.Size96; })