Weakest character to beat Castiel

[Global Alien]

Who can defeat the Winchester's favorite ally without stomping him?

[Sharkerbob]

Under ideal circumstances, even a normal person could do it, provided they have an Angel Blade and can get the drop on him. Crazy-mode Sam managed to do it, and it only failed due to the Purgatory power-up. Heck, even in Purgatory, he was getting slapped around easily by Leviathans, who despite having angel-kill powers, really shouldn't be a threat to any angels considering the speed at which angels can operate. Actually, same with certain demons who could hold their own against Angels. I guess Angels just have shit reflexes.

In actual direct combat against Cass at his prime, probably it would take another angel. Or, if speed really isn't something they can use to fight, then perhaps Nightcrawler with an Angel Blade can surprise him with a teleport back-stab, assuming Cass doesn't just use a time stop or do a teleport-stab first. If the person can't have an angel blade... well, there is the Colt, too. If they can't have any special equipment... it's hard to say. Really, the "can only be killed by very specific things" plus the time stop, time dump, dimension dump, super speed, nigh-instant regen makes him a tough cookie to fight without having to resort to stompier characters.

[T51R]

With, or without prep? That is the question.

[Dr Will Hatch]

Er...Nico Minoru with the Staff of One?

[Global Alien]

Just wanted to add that Cass is in the 1 ton plus strength weight class, and he can also turn invisible.

[big_adventure]

The show, like most things, writes speed poorly (at best). Cas has shown high-end reaction speed both out and in combat, and just typically forgets to use it.

You add time stop, time dump, d-dump, the ability to assume a true form that will kill mortals to see (apparently), the fact that ONLY Leviathan (never adequately explained), angel blades and the Colt can kill him, flight, teleportation, strength, telekinesis, telepathy, "smiting" and his own archangel (not just angel) blade and Cas is a tough kill.

[T51R]

Final Form Kurohime maybe, at a bare minimum. If she uses that last, planet-breaking Mahoudan/sword thingy I don't think Cas has the feats necessary to survive that.

How about looking at Balthazar's Junk?

[abmccray]

Cheating, but, an archangel (ie Gabriel). (it's much easier to just name the next higher up angel)

[Sharkerbob]

Cheating, but, an archangel (ie Gabriel). (it's much easier to just name the next higher up angel)

Well, you don't even need to go arch, another angel of Cas's type can do it, if he has the combat skill to outfight him.