"When on water terrain this figure is Stealthed and may attempt Regeneration."
This is an extension of the Submerged Feat Card and the known revitalizing effect of the water on Aquaman (as already reflected by the Regeneration that appears on one of his dials).
"Adjacent teammates do not take pushing damage."
This is adapted from the Inspiring Command Feat Card, and is a reflection of Aquaman's abilities as an inspiring leader (as already reflected by the Leadership that appears on most of his dials).
"The figure may attack with Psychic Blast within a range of 6 for damage of no more than 1."
Aquaman's hasn't frequently been shown using his psychic abilities against opponents, but there's certainly precedent. The limitation that he can only do one click of damage keeps it within reason.
This card helps Aquaman play more like himself. Using it, you'll want to keep Aquaman in the water as much as possible where he's stealthed and immune to ranged attack (except from pesky Superman types). From there, he can annoy your opponent by using his telepathy to pick away at the other team.
When the time's right, let him pop out of the water to clobber someone. Because this card grants him Stealth in water, you can also give him the Ambush Feat Card, (which will work really well if youuse this card with the Ambush Feat Card!). An Aquaman suddenly making an attack with a value of 12 or 13 will make quite a splash!
Once he hits dry land, he'll start to take some knocks. If he's weakening, have a friendly figure (such as Wonder Woman, J'onn J'onnz, Animal Man, or Vixen) fly him back to water terrain, where he can attempt to heal himself and come back fighting.
Take some superfriends who have range (like Superman, Green Arrow, or GLs John Stewart and Kyle Rayner) and array them in front of him. While they protect him, his encouragement will grant them all Willpower, for quite a killer combo!