I think you could have gotten equivalent results on such a predictor using much simpler regressions and/or heuristics, once you've already fixed the matchup.
(Also, I just think it's funny how the paper keeps citing "(Zheng, 2020)", etc, like it's a scholarly article or something. Aaron Zheng is a VGC YouTuber and what is being cited is just an online guide a la GameFAQs)
However:
> your opponent's team is only partially known (you see their Pokemon species but not the moves, stat distributions, etc)
That's not true in the main competitive live format (e.g. NAIC 2025 which is the main case study here). These tournaments are "open team sheet", aka. moves, ability and held items are known (but not IVs/EVs).
I'm not sure whether this is the case on Smogon though, which means they might even be mixing two completely different datasets...
And even then these can be guessed or even inferred using previous battles as an indicator.
Nit: there are 15 possible lineups (i.e. combinations of 2 pokemons to start the battle with) but there are 90 possible teams if you also factor in the other 2 pokemons in the back.
I have recently started watching a lot of WolfeyVGC and so the graph of incineroar being the most used etc. are so true.
There are a lot of other things that smogon does like the best hacked pokemon (ie. you can get abilities / movesets but not anything else, and some are banned like wonder guard) and there blissy with the transform ability is the strongest.
Honestly, Pokemon VGC isn't that balanced. Incineroar / IIRC before it, there was thundrous. But still its decently balanced that the game works. WolfeyVGC is an absolute delight to watch!
I might try my hand at this problem using the open sheet format for more data.