Both points in its favor, both not mentioned by them. Koko gets beat ez by Shuckle, too. And HP Ice is ofc great, probably better over Nature's Madness.
You didn't give any reasons for any of these. Just mentioning that the three megas get an advantage from electric terrain doesn't change anything because that's been true since day 1 lmao, Ultraballz actually pointed out that the recent introduction of Medicham and Mawile works in its favor as they appreciate the switch in. Moreover, Megagross doesn't run thunder punch as often anymore. Part of it is that he just presented his post as an actual argument.
Koko also has to correctly predict what Smeargle will do. It's a 50-50, in the favor of neither. If anything, the safe plays for each are magic coat and taunt, and so it's actually in Smeargle's favor.
I read it. That's not a point in its favor. It's had electric terrain boosting STAB since the first day of release. An argument for rise would be saying shit like "Megagross is running thunder punch more often, and Medicham runs it more and more specifically due to its partnership with Koko."
If I said "CharY hits hard as fuck with Fire Blast due to its insane SpA and Drought and thus should be A+", that's not a good argument. CharY has had a hard hitting Fire Blast since XY. Its power hasn't suddenly changed for its rank to change. An actual argument would be "Due to the lack of strong relevant fire resists in the meta right now that also don't take SE damage from Solar Beam, CharY's switch ins are limited to Chansey, Toxapex, Heatran, and Zygarde. Chansey is run almost exclusively on stall, and stall has decreased in popularity due to the strong stallbreaker sets gaining in popularity as well as the strong breakers like Mawile and Medicham destroying stall. Toxapex is also mostly run on stall, as toxapex offense has decreased in popularity since Phero's ban. Heatran is hit by focus blast and can't do much to CharY regardless. Zygarde can actually switch in, but only a few times, unless it gets time to take advantage of lefties. But Zygarde is running band more and more, which limits its switch ins since it has less bulk investment and no lefties." There's a difference between enumerating a man's qualities that it's had since day 1 and enumerating why the meta has shifted more towards it.
Note: Not advocating for a CharY rise.