I would like to discuss sub seed. We gained 5 new sub seeders this gen (Tropius, Scovillain, H-Electrode, Brambleghast, and Arboliva) (relative to gen 8 randbats) and while I could talk about all of them I'll talk about the ones I find rather strong first.
Scovillain- It certainly lives up to its name. Sub Seed Moody? This is certainly a combination. Glalie has ways of defeating it. It's still largely at the mercy of Moody rng and sub protect can still screw you if the opponent has a reasonably fast mon or priority. If Scovillain comes in on a mon that is threatened by Flamethrower, it basically gets up a sub for free. It has the special attack and base power to actually threaten a fire-weak mon. It also fares well against many mons that arent strong to begin with. If I get it, I win the game almost every time. If I'm against it, I have to hope I have a way of dealing with it. And what type is immune to Leech Seed? The same one weak to fire. Tropius has a similar issue but I'll get there when I get there. So, who beats this thing? The first answer that comes to mind is Unaware. Well, I can say from experience Quagsire doesn't. I 1v1d it and after that you can imagine how things went. Skeledirge can be hampered by Tera Water and Sub to block burns (all while farming boosts), DonBozo does beat it (I think) assuming Scovillain doesnt get the right boosts. I have no experience with Clod but I have low expectations. What else might help? Magic Guard? Nobody has that in this meta. Not randbats' fault of course, just incidental pool problems, not that Zam beats Moody anyway. Magic Bounce, which at least there are 2 mons with, but it's dicey at best. Maybe Rapid Spinners can sort of try? I haven't had any luck with that, though other factors usually were preventing it from being useful, and you waste time with a 50 BP non-stab move anyway that at most helps you outspeed if Moody has not screwed you. But if you get your 2 free turns of boosts (or get any way of firing off the Leech Seed) that automatically adds to the snowball. So, yea, I think moody leech seed is way too much.
Tropius- Basically the opposite problem of Scovillain. Instead of threatening the target out, it sits on it and doesn't die. It's already pretty bulky, and can spam Harvest to assist its Leech Seeds, which when combined with Sub give it more opportunities. Now, there are some mons that do beat it at least. It's fairly slow, is quad-weak to ice and still weak to other good offensive types*, hits like a wet noodle to mons that aren't weak to it, and will run out of pp eventually if you get counterstalled. You can also Toxic it if you are fast, though because of the transfer purge there are very few mons that even get it and one of them (salazzle) is already sub seed without being sub seed*. Same rules with abilities also apply (I won't restate them). But again, it has a move super effective on the type immune to Leech Seed, and can flinch if a mon happens to be slower than it. Speaking of slower, Spinners can't do much if they aren't breaking the sub and the seeds get back up. And to address the *, what is the tera type? Steel. Obviously you have to use your tera wisely, but if Steel is no longer threatened, you can go back to sitting on everything. I do have some success in beating Tropius, but it required game-long outplaying of it,
such as one game where I managed to bait the tera early. Counter subbing does work if you are faster and not weak to flying, at least, but I don't recall there being too many of those. It's still a crapshoot, though.
Brambleghast- I like the idea. I really do. And it's far lower in annoyance than the previous two mons. Instead of Protect, it gets to attack and protect at the same time with Phantom Force, letting it have either Rapid Spin or Power Whip. The issue comes with its speed and good defensive typing for a sub seeder. It can't be spun on, has 2 immunities, and Dark's presence has waned in the advent of the transfer purge. It's not weak to U-turn either. Tera doesn't really matter for this one. I'm pretty sure it just gets its stabs which don't really do anything notably egregious. I'm ok with this one on paper. I have been able to beat them a reasonable amount of the time, I just wanted to mention it.
Arboliva- I haven't experienced this one yet but from what I have heard (if it is accurate) it's like an alternative to Tropius. I don't recall its tera type, but if it has Harvest that is self explanatory and Seed Sower can be an issue depending on what attacks the opponent can use because then it is regaining a lot of HP per turn.
H-Electrode- Its only real notably annoying trait is its speed, but at least basically any grass type walls the crap out of it and because it is fast and weak to bug a U-turn will hinder its progress. I figured I would just mention it since it was new.
Essentially, I find the playstyle rather dominant if you don't have one of the limited available ways of dealing with it. I think in the very least many a few more faster sub mons might help somewhat? I would love to see Scovillain's win rates.
Not to mention half these mons are mid at best and are gonna get comparatively stronger as they drop tiers.
oh, also, my apologies for the incidental double post on scovillain. as you can clearly see, i was writing that entire thing concurrently with when the other post was made, so i did not see it until after the fact.
