Firstly, I'm not sure why many people here are proclaiming HO as brain-dead. Maybe it doesn't need as much long term strategy as balance but it's far from brain-dead click buttons - U just got predicted lol.
I'm convinced that half of these stall freaks just want to have the forum open on the other screen while they click recover for the 5th time in a row. Literally the definition of brain dead, way too easy to recover from mistakes or misplays. Meanwhile a misplay in HO probably means death.
On to the mons.
Gambit: I'm not totally confident on it being 100% broken. It is a fantastic revenge killer for HO, the next best being Iron Valiant who can often only revenge once. Scarf mons are ok but kinda a bit bad vs non HO, and many of the best scarfers would prefer a different item.
Revenge killers are truly necessary. This meta is very setup oriented. Not just in HO, you all know the HO setup abusers. Even balance and stall have a large amount of setup, gliscor, dondozo, zamazenta, blissey, cresselia, gholdengo, sinistcha, Scizor, clefable, garganacl, there are so many Pokemon with the potential to setup and sweep - even easier to do it when a mon is locked in with scarf.
On the other hand, gambit makes many things way too easy. It's even somewhat viable to slap 5 shitmons and gambit on a team, you'll probably do ok. The relatively easy damage boosts are somewhat uncompetitive - it does need them for many of the scary calcs though, so it is possible to counter/outplay. 3/5
Ogerpon wellspring: this thing is probably as crazy as hearthflame. Effectively 120 BP high crit move is probably way too strong. Too easy to click. Does wall manaphy and many horrible rain abusers. Still probably 4/5.
Manaphy: probably look at this after ogerpon goes. Whatever you say, 100 base SpA and Speed is mid this gen. SpA is workable, but the speed is a bit of a pity and as a result the mon needs either rain or webs. 2/5
Gliscor: oh I really hate this mon. Toxic heal is a genuinely uncompetitive ability. In a game where you win by doing damage to opponents, an ability that lets you recover damage just by existing is inherently uncompetitive. That also goes for regenerator.
Imagine if there were offensive versions of those abilities: degenerator, where the opponent loses 1/3 of their HP when you switch in, or toxic attitude, where if you are poisoned the opponent takes the dot instead of you. Those would be unquestionably broken, and definitely banned. So why the double standards for toxic heal and regen?
(Gamefreak don't steal my ideas for gen 10.)
Aside: Regen, Scald, Pult, and Corv were probably the biggest factors in making gen 8 as stale and lifeless as it currently is. Get all those shits out. Gen 9 was better without scald.
Anyway, Gliscor has "checks and counters" if you count weavile/mamo. Protect toxic heal is one of the most brain-dead "strategies" in the tier. Even the defoggers don't beat him - anything that is ok vs EQ/toxic doesn't like to eat a knock off. Corv doesn't beat him either - maybe you get max layers off but you'll still be u-turning as gliscor gets up a spike. Ban this bastard, regardless of a gholdengo ban, it still wouldn't help, he beats all the removal.
Also don't come at me with Ting Lu or H-samurott. Both should go too.
Ting Lu is another bastard mon that nothing ohkos. To use the HO analogy again, something that ohkos everything with little to no counterplay is uncompetitive and banworthy. Why not this shit that nothing ohkos? It's way too easy to use. It's just not ok that there is a mon that you can freely bring out, with a 1000% chance that the offensive threat in front of you can't ohko you or in many cases even 2hko, and probably can't even do anything that would put Ting Lu in a bad position, regardless of predictions or misplays. That is uncompetitive. It's also got ubers level stats and way too easy spikes, barely balanced by its lack of recovery.
Hrott has a blatantly uncompetitive move. Don't think it's too crazy out side of that move but deserves a ban for that.
5/5 for these 3 bastards.
Gholdengo: the above 3 need to go first. Maybe after if glimmora and clodsire are problems gholdengo needs to go. Probably the biggest problem is the defoggers all lose to it - but minus gliscor, great tusk will beat it consistently again (hopefully). Probably deserves a look. 2/5.
Moon may indeed be a problem. Dark dragon is not the best attacking combo, but tera fly acro is very hard to beat without gambit. Worth a look. 4/5.
I'm convinced that half of these stall freaks just want to have the forum open on the other screen while they click recover for the 5th time in a row. Literally the definition of brain dead, way too easy to recover from mistakes or misplays. Meanwhile a misplay in HO probably means death.
On to the mons.
Gambit: I'm not totally confident on it being 100% broken. It is a fantastic revenge killer for HO, the next best being Iron Valiant who can often only revenge once. Scarf mons are ok but kinda a bit bad vs non HO, and many of the best scarfers would prefer a different item.
Revenge killers are truly necessary. This meta is very setup oriented. Not just in HO, you all know the HO setup abusers. Even balance and stall have a large amount of setup, gliscor, dondozo, zamazenta, blissey, cresselia, gholdengo, sinistcha, Scizor, clefable, garganacl, there are so many Pokemon with the potential to setup and sweep - even easier to do it when a mon is locked in with scarf.
On the other hand, gambit makes many things way too easy. It's even somewhat viable to slap 5 shitmons and gambit on a team, you'll probably do ok. The relatively easy damage boosts are somewhat uncompetitive - it does need them for many of the scary calcs though, so it is possible to counter/outplay. 3/5
Ogerpon wellspring: this thing is probably as crazy as hearthflame. Effectively 120 BP high crit move is probably way too strong. Too easy to click. Does wall manaphy and many horrible rain abusers. Still probably 4/5.
Manaphy: probably look at this after ogerpon goes. Whatever you say, 100 base SpA and Speed is mid this gen. SpA is workable, but the speed is a bit of a pity and as a result the mon needs either rain or webs. 2/5
Gliscor: oh I really hate this mon. Toxic heal is a genuinely uncompetitive ability. In a game where you win by doing damage to opponents, an ability that lets you recover damage just by existing is inherently uncompetitive. That also goes for regenerator.
Imagine if there were offensive versions of those abilities: degenerator, where the opponent loses 1/3 of their HP when you switch in, or toxic attitude, where if you are poisoned the opponent takes the dot instead of you. Those would be unquestionably broken, and definitely banned. So why the double standards for toxic heal and regen?
(Gamefreak don't steal my ideas for gen 10.)
Aside: Regen, Scald, Pult, and Corv were probably the biggest factors in making gen 8 as stale and lifeless as it currently is. Get all those shits out. Gen 9 was better without scald.
Anyway, Gliscor has "checks and counters" if you count weavile/mamo. Protect toxic heal is one of the most brain-dead "strategies" in the tier. Even the defoggers don't beat him - anything that is ok vs EQ/toxic doesn't like to eat a knock off. Corv doesn't beat him either - maybe you get max layers off but you'll still be u-turning as gliscor gets up a spike. Ban this bastard, regardless of a gholdengo ban, it still wouldn't help, he beats all the removal.
Also don't come at me with Ting Lu or H-samurott. Both should go too.
Ting Lu is another bastard mon that nothing ohkos. To use the HO analogy again, something that ohkos everything with little to no counterplay is uncompetitive and banworthy. Why not this shit that nothing ohkos? It's way too easy to use. It's just not ok that there is a mon that you can freely bring out, with a 1000% chance that the offensive threat in front of you can't ohko you or in many cases even 2hko, and probably can't even do anything that would put Ting Lu in a bad position, regardless of predictions or misplays. That is uncompetitive. It's also got ubers level stats and way too easy spikes, barely balanced by its lack of recovery.
Hrott has a blatantly uncompetitive move. Don't think it's too crazy out side of that move but deserves a ban for that.
5/5 for these 3 bastards.
Gholdengo: the above 3 need to go first. Maybe after if glimmora and clodsire are problems gholdengo needs to go. Probably the biggest problem is the defoggers all lose to it - but minus gliscor, great tusk will beat it consistently again (hopefully). Probably deserves a look. 2/5.
Moon may indeed be a problem. Dark dragon is not the best attacking combo, but tera fly acro is very hard to beat without gambit. Worth a look. 4/5.