How Would Ben 10 Defeat Thanos Without Alien X Or Ultimate Ben?

   

     This post is not to say which character is stronger. But just to explain how Ben would defeat Thanos in a fight.
     We will not be considering Alien X and Ultimate Ben because they are too powerful and, at their full potential, would beat Thanos easily.

   

    For those who don't know who Ultimate Ben is, he is an alternate future version of 10,000 with the abilities of all his aliens in his human form.. Without having to transform anymore.. So it would be like a million heroes fighting Thanos at once..

    Ben's greatest weapon is the Omnitrix, he's not completely useless without it, as we have seen him fight without it once or twice. But without the Omnitrix, Thanos would easily squash Ben as he is merely a human.

    So we will be considering a scenario where Ben has total master control of the Omnitrix and Thanos has all the Infinity Gems..
    Since Ben would be the Hero, he will have to somehow defeat Thanos, because that's what heroes do.. So first we will see how Ben would counter Thanos' Infinity Gems.

 

1. The Space Gem/Stone:
                The Space Stone gives it's weirder the ability to teleport anywhere in the Universe. It won't be of much use because we've seen Ben's aliens surviving in Space and other extreme places.. So there won't be anywhere that Thanos can teleport Ben to kill him as the Omnitrix's failsafe will choose the alien necessary for Ben to survive. And in the future, we see Ben getting the ability to use Gwen's spells so he can use the Teleportation Spell to return back to the fight.
           

2. The Reality Gem/Stone:
                It allows its user to create any reality that he can imagine, it can alter reality itself.

The only alien that can counter this is Toepick.. It is said that Toepick's face is so horrifying and hideous that no being in the known universe can look at it without adverse effects, including fear, sickness, or even madness. So what else to counter reality altering than an alien that can make a reality so terrifying that it scares its victims into being pale white as a sheet.

3. The Power Gem/Stone:
                 It is made up of raw and unstable energy. It has the power to destroy planets. There are a few Aliens that could help Ben in fighting Thanos with the Power Stone.

When it comes to raw strength, Way Big (or Ultimate Way Big) would be most powerful alien for Ben to transform into. But the best aliens would be Chromastone, Feedback or Atomix..

Atomix is the strongest of them all, he's basically the Goku of the Ben 10 Universe..

But we've also seen Feedback absorb the power of the Anihilaarg which had the power to destroy an entire universe. So Ben could use any of them..

4. The Time Gem/Stone:
                As for the Time Stone, it allows its wielder to manipulate time in any possible way..

Clockwork would be the best alien for Ben to use in this scenario. We've seen Maltruant, who is also a Chronosapien, being able to create a Chronisapien Time Bomb, which works in a similar way to Thanos' finger snap, except on a multiversal level.. So Clockwork will definitely have the same, if not greater, power as the Time Stone when Ben has fully mastered the Omnitrix..

5. The Mind Gem/Stone:
                It grants to the user powerful mental abilities, like the power to subjugate the minds of others, bending them to the will of the user.

Ben has, possibly, the smartest alien besides Azmuth in the Universe, as claimed by Professor Paradox, Greymatter. And we also know that the Omnitrix provides Ben with the most superior form of the species that he transforms to, so it wouldn't be a surprise if Greymatter gets smarter than Azmuth. We also saw Ben giving his son Ken an omnitrix of his own, which could have been created by Ben himself.

6. The Soul Gem/Stone:
                   Its main power is to control souls, but what can Thanos do when he faces an alien with no soul..

Yes.. Ghostfreak.. The Soul Stone would be useless against Ghostfreak..

                 
                   After all of this, when Thanos won't be able to beat Ben by using his Infinity Gauntlet, he will try to beat Ben in a hand to hand combat..

And who better to fight Thanos hand to hand than the one and only Diamondhead.. Thanos may be an extremely skilled hand to hand combatant, but Diamondhead is possibly Ben's strongest alien when it comes to fighting someone hand to hand.. He is one of the few aliens that Ben had a lot of practice with, as quotes by Ben himself in Vengeance of Vilgax..

He beat Vilgax, the conqueror of ten worlds, like it was nothing.. He brought an entire species back to life and held the Chromastone Crystal with his bare hands.. A Crystal powerful enough to bring back a planet and an entire species back to life.

        And this is how Ben beats Thanos.