The round, yellow, and oversized head of a Sunflora, has drawn many comparisons to the Sun itself, especially because it is surrounded in golden petals which many have argued resemble the Sun's rays. This resemblance exists not by some accidental convergence, nor because it presents a larger face to the Sun, but because a Sunflora's head is little more than a case in which to contain a Sun Stone.
The Sun Stone typically lays dormant, and most of the pokemon's energy is obtained through photosynthesis. The stone is more like a battery than a generator, and it allows Sunflora the energy to battle hard at night or in the rain. But when a Sunflora is in danger, or enters a battle it is truly desperate to win, and their Sun Stone is of the right type (for many only make the Sunflora faster, like a water-type in the rain) its true power can be unleashed.
The body temperature of a Sunflora increases dramatically as the atoms within the Sun Stone undergo nuclear fusion. Their head glows like a miniature sun and spins rapidly as it shoots out Solarbeams so fast and piercing that many have said it was more like Arceus' grass-type judgment than the beams of even a Venusaur.
However, the Sun Stone's power comes with a cost. Not only is Sunflora's head often upside-down after it uses the power, but it exacts a heavy toll on the pokemon, which is often knocked out not by its foe, but by its own sun stone. After each battle, the Sunflora's head becomes a little smaller with it the Sun Stone it envelops. It is said that if the Sunflora uses up all the Sun Stone's energy, it will devolve into a Sunkern, a fate many consider worse than death.