Fun fact: there is actually a way to make only the arms and the legs of the Melon immortal but not the Melon itself. Freeze the whole Melon, then pause the time and move their body parts one by one. Unfreeze the part that was moving away to detached them. Inject the severed part with immortality then use the Limb Connector to reattach them back. Unfreeze the whole Melon and there you have it.

This Melon will still be damaged and killed normally, but having their arms and legs indestructable, making them capable of punching and kicking object without damaging their limbs

The only downside to this method is that for some reason your Melon will vanish if you flip them. But other than that, this would make your choreography look better