How can I make particles emit a burst once in Moon Animator?
Well you need to add the particle which has to be inside a transparent part to the animations timeline. Then after that you can edit it in anyway you like. Again the particle has to be inside a part which is either transparent (If its like a explosion then the part has to be invisible) or a part which is connected with the particle (like a flaming sword). That should help.
This plugin might help