sorry for late response, but forgot to post lul
for Popplio, I have talked about it in the past, but it's a bit more sophisticated to use, but it's capable of getting past quite a good amount of opponents. I'd have to check my logs for full summary, but basically, it makes a great use of Psych Up (with it, I have beaten Mimikyu, Kommo-o, and Ribombee) and is pretty good against other opponents like Nanu and Guzma. I understand the sentiments against it, as it's not an A-tier in the sense of spamming the A-button and winning, but rather it's something that can take on a lot of opponents with a little bit of planning
I could *maybe* drop it to B-tier if more people support this (last time we talked about it, there was an overwhelming amount of people supporting A-tier or higher), though
as for the rest, I'd say you are mostly spot on in terms of how they perform, though I see no reason not to give Marowak Fire Punch (BP is fairly easy to farm), curious to see what you think of the other Pokemon's current rankings.
as for any future runs, I think only Beldum could get a test. Bagon is a bit unnecessary to test unless you want to make a case for E-tier and I think there are more important things to test than Growlithe. However, *any* test is valuable, so do not worry if you want to try out those as well
I may also drop Vulpix to D-tier following a previous post. I'd like for this to revive a bit so I can do some other changes alongside it