When I've argued that Sora would not much more than a kid in FF, you claimed that he is an expert swordsman. He's not.
I'm reminded of a certain time when he sliced through seven buildings in the blink of an eye.
Sora's strengths all rely heavily on the Keyblade which grants him not only significant power but knowledge as well.
...no it doesn't. That's the same thing as saying that Cloud relies heavily on his sword to grant him power and that Squall relies heavily on his gunblade to grant him power.

He could not perform his best attacks or even fine attacks while using weapons like the stick, the Struggle club, or the Dream Weapons much less his invincible attacks or Drives.
1. He could still use Magic and abilities such as Sonic Blade with the wooden sword. He didn't lose these abilities when he lost Kingdom Key.

2. He could still use all of his Action and Support abilities that he learned on his journey when using the Struggle Bat, even Trinity Limit.

3. He wasn't as experienced as when he was using Dream Weapons. But he gained a lot of experience and fighting skills.

4. By the logic that you're using against me, Cloud and Squall is never shown to be able to defeat their enemies without the Buster Sword or Gunblade, so therefore I could make the exact same argument that their power comes from those weapons as well.

You've argued that Sora is more powerful because in the Final Battle, it was he and Riku who defeated Xemnas alone and it takes FF characters parties of 8 to 14 to win their Final Battle. This cannot be proven.
It can be proven because it's exactly what happened. The argument that Terra could have taken out God Kefka alone isn't any more valid than the argument that Sora could have taken out Final Xemnas alone.

It can also be easily disproven by a skilled player. For although you could claim a player's skills as being a gameplay element with no role in plot, the fact that a small party can defeat their final boss is still relevant.
But it doesn't change what the plot actually says happened. Sure, I could do a Solo Squall challenge against Ultimecia and win, and I could also hack KH2 into removing Riku from the Final Xemnas battle and win as well, but it doesn't change the fact that the story says all the FF characters worked together to defeat their final bosses and that Sora and Riku worked together to defeat Final Xemnas.

The strongest person at your gym and in the country are still part of the same reality. Thus this argument is meaningless.
Alright, the strongest person in my gym (located in the USA) vs. the strongest person in Russia. They are now completely different and completely unaffected by each other, which is practically the same thing as different realities.
More significant means more important, but it doesn't mean the guy from the gym isn't the strongest in the country, there's no proof offered of that.
There's no 100% certainty, but there is a 99.9999% certainty that the guy in my gym isn't going to be stronger than the strongest man in Russia.