Dialga can stop time with Roar of time for a whole turn in the games, idk for any other poke-canon.
It is, then, a question of start-up time – that is, how long the actual move takes before time is frozen.
Here we can see, from the animation, that it takes about two seconds for Roar of Time to charge, and a fraction of a second more to affect the target. As for Chaos Control:
As we can see, Chaos Control seems to take about 1.5 seconds – just barely beating out Dialga's Roar of Time. (Let alone the boost's instant acceleration, and the extra time it takes for a Trainer to command his Pokemon.)
Also worth noting is the fact that Roar of Time does not beat out defensive moves, such as Protect, Harden, and others. Thus, Sonic's shields, Super Sonic, etc will be able to block it, leaving Dialga vulnerable since it needs to recharge after using the move.
It is also able to erase people from existence when it nears Primal as shown in the Mystery Dungeon games.
He's survived that, actually. In Sonic Generations he's sent to the White Space, a land of nothingness – this is where time and space end up after they've been "erased" by the Time Eater. By speeding through these environments, however, Sonic is able to restore the worlds, and ultimately turn everything back to normal with the help of the Chaos Emeralds, escaping from the White Space into the normal world. Fortunately he has the Emeralds from the get-go here... so this wouldn't be very effective.
Also, Dialga's Primal state is due to the events of that particular game, and as far as I can tell cannot be initiated at will, during a trainer battle. (It was because the flow of time had been disrupted by outside forces, which would not be the case during this battle.)
Most psychic pokemon can use teleport.
Ah, yes, forgot about that.
Not exactly at light speed, but I know multiple moves from the games involving multiple attacks, including double team. There's also Future Sight I think it's called where it hits in the future, plus moves that hit no matter what a pokemon's speed, destiny bond kos the opponent if the one using it gets knocked out.
All of these, however, suffer the same problems as Roar of Time: they're stopped by defensive techniques (except Future Sight), and aren't fast enough to activate before Sonic's attacks. (If I'm wrong, please do correct me, I'm not very familiar with Pokemon, just going off of Bulbapedia here.)
Giratina has control over anti matter. Just showing how unique the abilities of legendaries are.
Interesting.