Well, er...
If you mean of Toku in general?
No kidding, no fan wank...It's going to be an Ultraman.
Just...well...yeah.
I'm not sure WHICH, and god knows that's a rabbit hole no one wants to go down, but its one of 'em. Most likely Ultraman King for...being able to do whatever the **** he wants, however the **** he wants, with his majestic fucking beard of ****.
But even in general. Let's look at...well any Rider VS any Ultra.
There's...nothing really ANY Rider can do to any Ultra in a straight up one on one fight, unless the Ultra was human sized for some bizzare reason. See, here's the thing, the only Ultras known to bum around, human sized, have been the original (forced to do so), UltraSeven, Tiga and Hikari.
....and of those four, three of them only do it ONCE for a very specific reason.
Seven's about the ONLY Ultra you'll find willing to be human sized at the start of a fight, ever. And...quite frankly, if Seven X is anything to go by, that's NOT a good thing for any Rider. Hell, if his ORIGINAL series was anything to go by....
And even if you, say, scale up the Riders to the Ultras height...
Well, as we see with Decade, who, by the by, was NO WHERE NEAR Ultraman's height, when he went giant size to fight King Dark...
Riders are very slow and ponderous while huge. Ultras...are not.
Still.
As far as INDIVIDUAL categories go...
Sentai-I can't speak on this. No real experiance.
Power Rangers- Dino Thunder, to me, has the most raw Power Houses of all the teams.
Kamen Rider- I've...no fucking clue. Kuuga isn't actually all that powerful, Ultimate aside (from what we saw). Kuuga's power comes purely in his kicks, or, in Titan form, being really tough. Even that's nothing too out there. Without relying on finishers, Kuuga is...a very average Rider. He's not that strong, he's not that fast, he's not that tough. Rising Mode helps, but not by much.
Then you have a Rider like, say, End of Show Kamen Rider Black, the fully realized Century King, who could take blasts that tore the earth apart something awful and DECIMATED buildings with ease head on and keep coming. Everything about him was POWERFUL. And if you give him the Satan Saber, he's a force to be reckoned with.
You might vote for Decade, given he has all the power of the past 10 Riders, or OOOs, for having SO MANY powers....
But they're actually fairly weak. It's REALLY easy to make Decade dehenshin with a strong enough attack, and beyond that he's just not that skilled a fighter and his attacks just don't pack that much of a punch. Let's face it, the only reason he killed so many Riders was because they were all AUs, AND most of them were entirely off screen.
Then there's OOOs, who has the lack of skill problem of Decade times a million. I like OOOs...but the dude cannot fight. He doesn't know how to. He has ZERO skill in using his powers correctly. Its just if one set of powers don't work, SWITCH FOR ANOTHER! That's...just lazy. And in a real fight of power houses, will get him killed quickly.
And I honestly cannot judge most of the other Riders, for I have seen so few of their shows. The Showa Era crowd, outside Black, are more limited if only due to their special effects and budgets, but could take some pretty neat things... (V3 training with a WRECKING BALL for instance) But the insanity of the super powers the new Riders get is a bit much to bare. So I dunno.
....though if Decade's Movie War is anything to go by, Kamen Rider ZO is more powerful then every single new age Rider put together. Though he might have issues with them if they all go into their final forms.
Maybe. (I will never let this go!)
And as for Ultras: If you mean Ultras who got their own series...I don't know. Possibly Ultraman Zero, though he's yet to get his own ACTUAL series. I'd love to say that it's UltraSeven...
But that wouldn't work. Seven is damn powerful, even for an Ultra, and has been shown and seen to do some crazy ****-but he's not THAT strong. Most of his 'strength' comes from something so few other toku heroes have.
He is a true, honest to god Determinator.
See, most Toku Heroes have the mentality of never give up...but damn if they won't COMPLAIN about the damage they've taken, or the beating they're receiving. Often, such as in Black, Black RX, OOOs.... if the fight starts to turn against them, they will utter a line such as "if this goes on I'm finished!"
Seven don't roll that way.
Let's look at the first fight to prove this aspect of his character-King Joe. King Joe is immune to his energy attacks, immune to his EyeSlugger, stronger then him, tougher then him, almost as fast, and inhumanly driven towards a single end.
Seven, despite learning all of this, not from word of mouth or villain bragging as is often the case (GLARING AT YOU RX AND COUNTLESS POWER RANGER VILLAINS) but in combat, mid combat.
...he never ever ever stops attacking King Joe.
To the point where, through sheer determination alone, he forces Joe to retreat after getting the **** beat out of him.
Their second fight?
King Joe is going to murder a whole bunch of people. The Ultra Garrison are developing a weapon that can punch through his armor, but need...a lot of time.
Cue Seven taking Joe on, head to head, for an ungodly long time, never once taking a step back on shore. He keeps Joe in the bay and doesn't let the bastard robot move a foot into the city, despite the fact that Joe *IS* stronger then him on every field.
And there are numerous other examples to show what a tough Son of A ***** Seven is in a fight. The crowning moment has to be...*ALL OF LEO*
But we'll start with the beginning of Leo.
Seven is, by himself, facing two rather powerful monsters and...doing pretty damn good all things considered. Then their master shows up and they over power him...and VIOLENTLY breaks his leg, twisting it a full 180 degrees at the goddamn knee.
Any Rider, *ANY* Rider, that'd be game over.
And it seems like that's the case here...Leo shows up and attacks the leader, saving Seven...
Then the monsters move in to attack Leo and Seven JUMPS BACK UP and physically holds them off while Leo fights.
Seven, the guy who just got his leg DESTROYED, gets back on his feet and keeps fighting. Because **** pain this is how you protect the Earth.
The best part? Seven then gets shot in the face by the leader, destroying his transformation item.
We know it destroys it because, after the trio of evil leaves and he FINALLY turns back to human (Not until they leave) he immediately tries to transform again and give chase...and can't because his transformation item burns up.
...and that's the only way to keep Seven out of the fight. Make him unable to transform or kill him. Good luck on both. ...only not even THAT stops him, as Leo will prove.
But what does all of this Seven wanking mean, you may ask?
There was a point, I assure you.
See, Seven, despite all of his badassery and manly toughness?
He doesn't hold a candle to Ultraman King.
Ultraman King, who, with a WAVE OF HIS GODDAMN HAND instantly defeated Belial, one of the most powerful Ultras ever, and then CREATED A MAN MADE MOON AROUND HIM TO BE HIS PRISON IN TWO SECONDS FLAT. That was the same wave of a hand, for the record.
...so yeah, no matter who wins, Ultraman King still wins.