So...the power chart.

1. kuja- Nuked/busted a planet, crossed dimension and space back to Gaia, forced the roots of the Iifa Tree out from deep within the ground, make a pocket world/dimension to get to the crystal.
2. Neo X-Death- A city-destroying mage merged with the powers of the Void.
3. Kefka- Could have easily nuked the entire planet on a whim but never achieved or showed this.
4. Ultamecia- Used Elione along with her own powers to compress time.