[@Old Amsterdam]

Meh.

Prescient is the most powerful, possessing the power to control the future. It's effectively impossible to defeat them because they know what you'll do in advance, and they can remove any outcome they dislike.

Clairvoyant is the second-most-powerful because she has some of the predictive abilities of the Prescient through mind-reading and can kill people with a thought. No other ability besides psionics can block or oppose her attacks, and she can attack without being present.

Venom is probably third. Plague is a powerful ability and can wipe out large groups of people. And being able to rearrange the biology of living creatures allows her to create incredibly powerful servants.

Electric is the second. Raw firepower and strength. He can blast pretty much anything apart, but lacks subtlety and versatility.

Island is the lowest, although not far behind Electric. The relation between them depends on exactly how much energy and mass Island and Electric are able to manipulate, but in general energy-manipulation is slightly better. And Island lacks the ability to deal with more versatile enemies such as Clairvoyant. A powerful psychic could take him out with ease.