Despite how bad I think it would be to kill another, I thought it would be really cool if we knew what powers the trolls and kids would have in their God Tiers. Just chalk it up being similar to ultimate weapon thread. This is subject to change and addition, just tell me what you think! If you want to also draw what you think their outfits would look like and post it here, go for it!
Dave (Knight of Time): The power to manipulate time down to each individual cell if not lower, and to speed up time for some other things. Perhaps the ability to protect the alpha timeline and/or doomed timelines if he chooses. Perhaps has a scratched up gear shield with a broken record symbol covering the front. Also wears ironically red tux like a ninja crashing a party, because he hides behind time like he hides behind irony.
Aradia (Maid of Time): The ability to repair and clean doomed timelines.
Nepeta (Rogue of Heart): To toy with the hearts of others and to switch their allegiances as easy as 1 2 3.
Terezi (Seer of Mind): Able to physically go into the minds of others and see everything from their greatest fears to their greatest desires all at the drop of a pin. Telepathy also entailed.
Jade (Witch of Space): The power to manipulate spatial distortion among other things without killing yourself despite copy/pasting pieces of yourself, and also taking out a chunk of your torso to dodge a weapon (teleportation). Also able to grow and shrink things. Probably also like Xigbar from Kingdom Hearts 2, may be able to shoot bullets out of her arms - courtesy of chrisKnyfe.
Kanaya (Sylph of Space): The power to travel great distances, and to move big objects such as hurricanes.
Karkles (Knight of Blood): The ability to teleport to where there is blood, and also to distinguish personality by blood maybe? I'm not really sure. Being a warrior and a knight he would likely also know the best places to hit for any creature in order to make them bleed out or to barely do any damage at all. He might have a knight's coif. Can change the color of others' blood? Courtesy of TacticGamer. Courtesy of The_Codfish: naturally brings allies together, seals deals, and knows a lot about blood/genetics/romance. Courtesy of Blue Lantern: he may have regenerative powers, maybe even becoming more powerful/dangerous the more damages it takes or causes.
Tavros (Page of Breath): May be able to carry messages over great distances, or rise up past something else using wind powers, or perhaps even move mountains and the like. Likely would have increased his ability to commune. Courtesy of Retcon and Skyrius. More potent breath of life? Courtesy of Seikouya. Might be able to ride the wind like a horse through the air at great speeds, and possibly spin like a drill.
Eridan (Prince of Hope): The ability to snatch victory from the jaws of defeat, and to see ways in which you can still win. Never giving up, and never running out of ideas.
codingTornado: Drifting a bit, Prince is quite an ample term, but it could refer not to the heir of a monarchy but to the ruling noble of a principate. In Machiavelli's most famous work, The Prince, he states that a Prince establishing a new Principate could win the people trust and favour by virtue or, in other words, by his charisma, blood and "good deeds" towards his new subjects.
So, maybe the Prince of Hope is one to take leadership in times of despair and earn his companions trust and support in this situation and make them go on even against the most disheartening odds. That, would seem to me, should be his role... but since he learnt nothing he is unable to fulfil his role.
Feferi (Witch of Life): The ability to give the kiss of life and return those who have been long dead, and to give life just by touching, and to perhaps give life to inanimate objects, thus including the echeladder for inanimate objects. A healer of different proportions.
Rose (Seer of Light): The ability to see all truth, without optimism and pessimism. To see who is who and what does what at the drop of a pin. She would probably look like an oracle, having detached sleeves and a bare midriff, with a long dress in her colors. She might even have a kerchief to wrap around her head.
Gamzee (Bard of ?): N/A. The ability to rain down such a firestorm of expletives upon your foes as has never been imagined (by Beelzebibble).
Vriska (Thief of Light): Stealing fortune and truth. Steal the spotlight. And steal the light to create darkness, courtesy of Pokolo.
Sollux (Mage of Doom): The power to predict death and also to reign doom on opponents, sort of like an RPG spell. It's speculated that had Sollux God Tiered he would have either become conscious in both dreamselves, or combined dreamselves to see it all at once, or perhaps would have been able to God Tier twice.
Equius (Heir of Void): I don't really know. The ability to void things from existence. May have inherited nothing. Thanks to Retcon and Skyrius. Courtesy of Mister Tambourine Man: Heir of Void... perhaps one who would adopt a destructive, nihilistic view of things? But what power could that grant? Will Equius be able to just punch something so hard it just stop existing altogether? His outfit would, as has already been suggested, would be very homoerotic.
John (Heir of Breath): Able to inherit the powers of wind around him (courtesy of Skyrius), and to use it to pierce and blow, going back and forth to create a tornado or else moving forward without stopping? More potent breath of life?
Unofficial Troll Symbols (feel free to use):
Courtesy of Tenebrais.