Is there anything you would change about the gameplay mechanics if you could? Like would you want to add any other stats? Or maybe raise the amount of HP Pokemon get?

Well…

Can I just say “yes”?

I mean, not to either of those specifically, but just in general… yes.  If you gave me control of those games I would rip out their guts and replace them with special stardust.  To explain everything would take months.  Luckily, this is exactly what I plan to do once I finish my Black 2/White 2 playthrough story.