Honestly, I think Daikenki's role (in either OU or UU) will be as a bulky attacker with access to priority.
Daikenki@Life Orb / Leftovers
Quiet; 252 HP / 6 Atk / 252 SpA
Aqua Jet
Hydro Pump
Ice Beam / Megahorn
Hidden Power Electric / Grass Knot
In terms of OU, Aqua Jet is nice priority, managing an average of 51% on 6 HP Doryuuzu and nabbing a decent chunk on other attackers. Hydro Pump lets Daikenki get in to fire off a powerful attack, while Ice Beam complements the set by hitting Grass-types (Megahorn, however, is still an option for hitting Celebi for the KO). HP Electric lets it hit other water-types, and Grass Knot does the same but trading hits on Vaporeon and Gyarados for more potent attacks on Swampert and Suicune. It finds itself playing similarly to LOMilotic, but with no priority over recovery.
In terms of UU (I don't play too much so bear with me), Daikenki is still significantly strong. Aqua Jet knocks off around 40% to 120/0 Neutral Arcanine, one of the bulkier fire-types of the tier, and obviously has its uses against the likes of RPRhyperior and physically frail sweepers like Mismagius and Alakazam. It sports the 3rd most powerful Hydro Pump in the tier, after Gorebyss and Omaster, and the set takes advantage of that. The lesser amount of dragons in the tier makes a stronger case for Megahorn over Ice Beam, which is about a 3HKO on Tangrowth, and is overall a powerful attack in general. HP Grass is probably superior over Grass Knot due to UU's lesser weight.