If you haven't updated the OP, do you have some unified comment that explains all of these (that is, excluding those that appear to just be from the OP)?
Well, I can write explanations specifically for everyone to make it easier to evaluate:
1. It has been repeatedly claimed that Voldemort is the most dangerous wizard and Dumbledore defeated Grindelwald in a legendary duel.
2. Credence gets this level because in the script he showed the level of destruction of the mountain
3. There is a spell that can lift a mountain out of the ground, bringing it down on the enemy. But since it has been demonstrated once, it cannot be used by other wizards. However, the duel between Dumbledore and Grindelwald has been described as the largest and most legendary among all the others, and obviously among the duel in which the mountain shift spell was used, so the magic of Dumbledore, Grindelwald and Voldemort must be at this level or perhaps higher.
4. Feats from canonical sources were demonstrated in which wizards accidentally or unconventionally used such forms of spells that led to powerful destructive consequences, but it cannot be argued that any other wizard possesses such magic, because Harry Potter is a limited energy system.
5. Dumbledore created a copy of Berlin in the third part of Fantastic Beasts
6. Spells that extend over a huge impact radius (meteor shower, creating copies of cities, creating mists over cities, etc.) have been demonstrated many times. Teleportation allows you to distort space-time in order to instantly move on an urban scale, and portkeys enhance this effect, allowing you to instantly move across continents.
7. Wizards are taught an expansion spell that allows them to expand the space inside objects so that it remains unchanged from the outside (Hermione's purse, Newt's suitcase). Dumbledore and Grindelwald also created a pocket dimension where time was stopped to conduct a duel.
8. We see that in the verse, the power of magic in most cases depends on the power of the wizard (Hagrid ignores some spells and scatters crowds of wizards, it is indicated that he does this with his great power and at the same time uses powerful non-verbal forms of spells, although he is not considered an outstanding student, since he was excluded in the initial courses). Credence is also a good example.
9. Some spells that are tuned to Hax can have destructive power and are controlled by wizards. Expelliarmus is demonstrated as Hax, which allows you to take away a magic wand from a wizard, but if the wizard wants, then a powerful impulse can occur when the spell is struck, which either pushes the wizard against the wall (example with Snape) or destroys the entire ceiling (example with Harry). There are many such examples, but I have given the most obvious one. Moreover, magic comes from spells alone and therefore electrical devices do not work at Hogwarts, since there is a huge accumulation of magical energy there.
10. In the duel, Albus calmly fights with Credence at kinetic speed (physically fights with him on equal terms) in such a way that shock waves spread around them, which destroy the earth and glass. At the same time, Cridens controls the Obscurus and uses it to attack.
11. In the script for the third part of Fantastic Beasts, it was indicated that when Dumbledore and Grindelwald's wands collided, they began to absorb each other's powers. A similar effect was also demonstrated by Voldemort when Ginny began communicating with him through Riddle's Diary.
12.
(5:15 - 5:40)
13. Many wizards were in the battle against Obscurus and could influence him through attack (the Aurors blew him up in the first part of Fantastic Beasts) and when Credence cut Newt's shields with his magic.