Kirby is a Voidborne, made from pure happy and friendship

His specific classification is an Astral

An Astral is a Voidborne who isn't Dark Matter. So essentially one who leans anywhere from the negative side (not enough to be Dark Matter tho, that takes a more specific type of negativity), neutral, to positive

Astrals tend to prefer sugary stuff over other things. It has the energy stuff that they need.

They also have a strong moral compass, and can be very hard, of not impossible to change