Op, when you're analysing Bitcoin volatility and referring to information like '7 out of 12' Septembers being bad, it would be good to see sources, so that one could understand how it was measured, against what etc. Right now, Bitcoin is just 14% below the ATH, which I would say is great because it is rare that Bitcoin is so modestly below the ATH point. But if it's measured by average price compared to the previous month's average price, that's a different story, and we'll see September's results pretty soon as the month is nearing its end.
For Ethereum, I think it often follows Bitcoin fluctuations, more or less. As for US election debates, I think Bitcoin has already experienced the main bulk of elections-related fluctuations when Trump made a campaigning point out of it. I don't think we'll see much up until the elections result.