It seems to me that Latios's issue with being a scarfer is his less than amazing physical bulk not his "strength". When the vast majority if priority moves are physical, having a scarfer that doesn't resist extremespeeds and brave birds is much more risky than in the past.choice scarf can't be used for revenge killing when these three monsters are giving the metagame headaches just from priority
there are obviously others but these are the 3 who can sweep with their priority alone, after playing a team with all 3 of them on it, i think we can compare it to scarf users. on top of all this, they are so versatile that they can run multiple sets to go with their priority
we can't use scarf users for strictly revenge killing like we could in the past, they're not strong enough, they need to have another role, like a sweeper, wall breaker, something else, for example: scarfchomp is much more than a revenge killer, in fact, it's probably better to describe him as late game clean up, he functions like those three do in that they can be used for revenge killing but do the late game clean up fantastically well
scizor was the first pokemon to do this with priority, able to do more things with priority besides revenge killing, then we got breloom who could fuck over teams with spore and then sweep with mach punch but as these were really the only two priority abusers we got, we still needed scarfed revenge killers for team function (dnite was off doing abusive things last gen)
now that priority is fucking everywhere, it's probably best to look at it as not revenge killing, but for sweeping and that's what we need to view choice scarf as, not for revenge killing but for sweeping with something absurdly fast
which probably means the scarfer needs to be stupidly powerful like garchomp, excadrill, or staraptor. heck, latios is even struggling now to be a good scarfer as it's not "strong enough"
Eeyup.While [Deoxys-S] doesn't have particularly impressive attacking stats, it makes up for them by essentially being a Choice Scarfer with a boosting item (that can also switch moves). If you compare its attacking power to that of other Choice Scarfers, it does a lot better (calcs using coverage moves because you already admitted that Psycho Boost is powerful):
252 SpA Genesect Ice Beam vs. 4 HP / 0 SpD Latias: 148-176 (49 - 58.2%)
252 SpA Life Orb Deoxys-S Ice Beam vs. 4 HP / 0 SpD Latias: 164-195 (54.3 - 64.5%)
252 Atk Garchomp Stone Edge vs. 0 HP / 0 Def Manaphy: 109-129 (31.9 - 37.8%) -- 0.3% chance to 3HKO after Leftovers recovery
16 Atk Life Orb Deoxys-S Superpower vs. 0 HP / 0 Def Manaphy: 110-130 (32.2 - 38.1%) -- 1.4% chance to 3HKO after Leftovers recovery
Again, it gets this power while outspeeding every common scarfer, but being able to switch moves as well.
Thanks for saving me from having to type that up again myself. Yeah, Deoxys-S is so great that I can barely ever justify any Choice Scarfer over it. The only reasons I would consider one are U-turn, better STAB type, or extra stuff like Rapid Spin on Excadrill. As a fast revenge killer, it's really hard for any choice scarfer to be as good as Deoxys-S.I also think one of the most important "scarfers" to consider is Deoxys-S. The life orb set essentially plays the same role as a scarfer, since it's essentially a scarfer that can have a boosting item to augment its attacking prowess (and doesn't get locked in). I shamelessly quote TooMuchSugar from the viability ranking thread:
Eeyup.
Ok, to be fair, espeed dragonite is nothing new and has been both around and viable ever since dragon dance became a thing, if not sooner. But yeah, I think that the reason why priority is so much more dominate this gen then any previous gen is one thing and one thing only, power. Last gen, unless you're hitting for SE damage or are boosted, even smeargle could survive a decent majority of priority thrown at it, let alone something with non-laughable bulk, and still have a chance to retaliate (ok, that was an exaggeration there). However, today we have things like azumarill, talonflame and pretty much every much every single OU mega not named mega-heracross, who even unboosted, can 2HKO or even OHKO many faster threats before they even have a chance to move.Choice Scarf seems to be becoming the niche that priority once was, something that's nice to have from time to time but no matter how many life orbs you gave your Breloom it wasn't going to put more work in than specs Keldeo and whatever took out Specs Keldeo after something died before your entire team fell apart. So todays "specs Keldeo" is something more along the line of ridiculous power house megas that will deal over 100% to about every mon that doesn't have intimidate with max hp and def, and then has a coverage move to OHKO it anyways, as well as Talonflames priority. So really the only things we're labeling as something under "need" on it team is the same thing we've always needed, counters and checks/revenge killers for the top threats in the meta-game, Tyranitar may be used to counter Talonflame, but surprisingly a scarfed Tyranitar can outpace Mega Pinsir and kill it with Stone Miss before either getting destroyed by Close Combat or Earthquake. He isn't the fastest in the game by any means, still being outsped by Alakazam even with the scarf, but really his only requirements for it is that he can handle 2 top tier threats, but still has to watch out for the rising of Mach Punch and Belly Jet.
Just on the topic of Mach Punch and Belly Jet, sashed Breloom and Belly Jet Azumarill have been pretty common since the start of the generation. The fact that you can swap an Azumarill into some feared fighting type such as Conkeldurr and get a free Belly Drum with a Sitrus Berry recovering the majority of your HP and the only thing that seems to stop this once it come up isn't some scarfed Garchomp that wants to break that last 50% with Earthquake, but something more along the lines of the bravest bird, sash living a hit depending on how many hazards you can defog away, and trying to have a hard counter just for this situation. No matter what scarfer you use you can't say you'll revenge kill Azumarill at +6 unless you run something with supreme bulk and a resistance to water, so why is it incredibly necessary to have 400+ speed scarfers, it seems other than priority the only thing you need for a successful scarfer is being faster than a fully speed invested base 110 with a check/counter to Greninja or having something a little bit faster that can handle Greninja on its own.