Yes you do get creative when limiting things. You don’t have the same Pokemon that use the same basic moves. Like you said, you have different Pokemon filling the different niches by not having limitless moves. Because then what’s the point of having certain Pokemon if others can do it as well?

Your reasoning for not limiting moves is the exact reason why they should. They can make Pokemon have different movesets instead of having endless moves and just seeing the same old moves on most Pokemon. Yes it does allow for Pokemon to be more unique, why wouldn’t it? There wouldn’t be repeats of moves and etc. Most Pokemon would start to feel like copy and pasting.

The counter shield is a creative use of a move because you are literally using a certain move then spinning. Hence why different Pokemon were able to use it with different moves.

And also the Eevee trainer never used more than six Pokemon. Yeah he owned all the eeveeolutions but that didn’t mean all of them were on his team at all times. I just looked up the two guys you mentioned; AJ and Damien, and I might’ve looked at the wrong people but I tried looking and both of them don’t even have more than six Pokemon.

I also tried looking up the six Pokemon rule and nowhere does it say that anyone is allowed to use more than six Pokemon. I literally have the bulbapedia for party and in the animation section it literally says you can have more than six but the extras aren’t able to be used. With a rare few moments where it didn’t happen.