>>19301454How do you define power?
Specs Kyogre Water Spout in Rain.
150 base SpA + 150 base move + 1.5x Specs + 1.5x STAB + 1.5x rain
Needs no turn to boost, just comes in and demolishes all non-uber tier bulky resists/immunes. Can still Hydro Pump at lower HP values if you find Water Spout to be objectionable.
If it's merely the damage outputted, then you can create long winded scenarios with +6 Power Trick Rollout Shuckle against -6 4x weak mons.
Geomancy Xerneas dominates Ubers right now, but requires a turn of setup.
Arceus can run a bazillion sets viably, making it effectively have no true counters, since it can always run a different build; there is no one Pokemon that will ever counter Arceus in all of its possible forms.
Your question is poorly worded and left ambiguous, not unlike those 'tricky' math problems found online with no parenthesis to supposedly have multiple answers.
