You dont give any arguments on banning them other than showing their raw base stats. (Not to mention Kyurem-White was already banned before it was even released...)
To give you an example why raw base stats dont always mean its overpowered: Kyurem-Black has 170 base ATK but no viable physical STAB Ice move which is a huge aspect which you can not ignore while looking at its base ATK and stats in general. Kyurem-Black is strong but not overpowered at all.
To list some further weaknesses and how to counter it better:
- Weak to stealth rocks
- Gets worn down quickly when running life-orb to keep it versatile
- 95 base speed is good but not insane for a wallbreaker so it can be revenged-killed, especially when locked into moves like Outrage or being choice-locked to boost its power
- Weak to common typings like steel and fairy + 5 weaknesses overall
- Weak to rather common priority moves like Bullet Punch and Mach Punch
- It cant carry all moves to counter every pokemon: Fusion Bolt, Ice Beam, Earth Power, Outrage, HP Fire, Subsitute
-> scout for the moveset, keep your fairy and steel type healthy
(I am no PvP expert so dont take criticise every word to harsh)