>>46196200>THE MOST POWERFUL POKEMON™Mewtwo, which took the best of Mew's genetical potential (which, in turns, includes every single pokemon's genetic potential) and is at the peak of pokemonkind's biological/energetical/metaphysical capacity for raw power. Note that it's about the capacity, not the ability — Mewtwo as shown is young and extremely inexperienced compared to what it could become (thus its reliance on psychic powers; though it is an intuitive user of Aura too, and its Mega-X form is a proof that its capacity for physical development is no less formidable if it'd choose to develop that way).
Moreover, it has two flaws that might (or might not) truly prevent it from eventually becoming a true godlike being. First, it's engineered for battle, so humans took out what they perceived as unnecessary — that is, the potential for "peaceful" powers; Mewtwo can literally rend space and roar the time just like Palkia and Dialga do, but can it dig, dive, transform? Does it have power over earth or a lowly twister? Nope.
And the second flaw is that its mental, especially emotional, development has been stunted, thus in turn stunting the development of Mewtwo's powers. Perhaps one day it will solve all of its issues and start on a road to self-perfection, but until it happens, all this more-than-godlike potential is trapped inside a being that's too flawed to properly wield them.
Outside of the violence.
>The RUNNERS-UPDeoxys, which is a super-adaptable, newly-introduced to PokeEarth being (pokemon or not) that can, and had, extremely adapted to extreme violence.
Uxie and Azelf, if they choose to invoke their powers
FUG, which polices other legends and defends the sky from evils like Deoxys and, worse, Cleffa.
Arceus, which is still a creator god and a master of all 18 elements.
Zacian and Zamazenta, according to their rep.
>UNLIMITED RAW POWER, NOT ENOUGH CONTROL TO USE IT COMPETENTLYNecrozma in its fused/Ultra states and Eternatus.