If anyone is still here, I have things to add to that statement about Kirby and Void. In various pause screens for Void, it sends the same general message: "No telling if it's true, but according to the ancient scrolls, Void Termina may rise again in other forms depending on whether positive or negative energy is gathered (input before its "Astral Birth"). It seems this being of darkness will wander the galaxy until one day he is reborn into a new existence. When he returns, hopefully it will be... as a friend." -Void soul pause description. Also, in the pause description for Void, the true final boss in Soul Melter EX, it says "The final battle at hand, Void takes his first steps toward a new age. In place of tyrannical rage, will he find...naptime? Gentle breezes? Treats? He may even dream again... A dream of friends united!" Huh! Sounds an awful lot like Kirby's likes and habits. Furthermore, in the "Boss encounter art" or whatever you call it, the background for Void is the same as the red, blue and yellow one in Hyperzone 2... Where you battle Zero. In Hyness' chants, he is essentially promoting the "Dark lord" (Void Termina) to rise in "despair". He sacrificed himself and the three mage sisters, beings so full of hate, and only dark hearts into the Jamba Heart. Negative energy input. When Void is defeated, the last thing that can be seen is a silhouette of a smiling face like Kirby's. Void is constantly changing its expressions during battle prior to this. Why? The darkness Hyness input was getting to it, but Kirby and his friends made him want to be different. Kind, helpful and carefree (unless Popstar is under attack which is a frequently occurring event in the Kirby series!) just like Kirby.
What am I getting around to? Essentially, with all this context, it can be inferred that Void is the beginning of either the species of Kirby, or the species of Zero. If negative energy is input before it's astral birth, then it will be a Zero. If positive energy is input, then a Kirby. But the question is... Were Kirby and Zero born at the same time period, the original battle of the four heroes of yore and Void Termina, the battle to seal the darkness away? If so, why was there one being with positive energy and one with negative? Well, Kirby context states that Galacta Knight, the only confirmed one of the four heroes, strongly stands for anger. Whether it be the music, violent attacks and general hasty movements, he seems in a constant fit of rage. So, my theory is that 2 of the four heroes were rather full of negative emotion, and the others positive. So during the battle, some negative Voids were spawned by Void Termina and some positive ones. Really sets the mind racing if that theory is true!
Another question is, what if Hyness succeeding in summoning a fleet of Zeros if only negative energy came face to face with Void Termina? Well... That couldn't be good, even for Kirby, a being of infinite power.
Well, sorry it's a lot, but I take the depth of Kirby lore into... Well, deep consideration- If anyone is still here then I hope you enjoy my thoughts about it!