Suggested by Destroyer Hibito has a pretty cool fire sword and a lot of elemental attacks but I don’t think that would be enough to stop Dialga. Dialga is one of the most powerful Pokemon on the planet and is the master of time. Hibito can move rather quickly but he won’t be able to dodge Dialga’s onslaught of attacks or outmaneuver them long enough to secure the win. Ultimately his efforts here would be futile. Dialga wins.