0 Atk 1 IVs Neuroforce Necrozma-Ultra Stone Edge vs. 248 HP / 204+ Def Ho-Oh: 420-495 (101.2 - 119.2%) -- guaranteed OHKO
0- Atk Neuroforce Necrozma-Ultra Stone Edge vs. 248 HP / 204+ Def Ho-Oh: 410-485 (98.7 - 116.8%) -- 93.8% chance to OHKO
Always getting that OHKO on Ho-Oh is pretty important, especially when it is the main entry hazard removal of the tier and Stone Edge already has some accuracy issues. The dex revamp is underway and there is an argument that defensive Ho-Oh being close to non existent outside of stall should be factored in when/if this is redone.
The reason to use 1 iv in attack is for using photon geyser as a special attack pre-ultra...but why no runing this instead?:
The 1 Atk IV is to maximize its attack while keeping Photon Geyser special so it doesn't proc Glimmora's Toxic Debris while maintaining the ability to block Mortal Spin pre Ultra Burst.
Is worth that 5 extra atk points over the 26 extra sdef points?
I think no.
In my opinion Power gem should be mentioned or even slashed first because hits Yveltal harder but that is optional and should be used with 0 iv attack and only if the QC says that is good idea.
The only reasons for runing Stone edge over Power gem are:
Better damage when no ultra.
Better rolls at OHKOing Ho-oh at full health.
This was discussed a lot during the process which you can find in the NDUbers discord if you're willing to scroll back to I think Febish in analysis discussion. The discussion on this topic primarily pertained to whether Power Gem should be mentioned as an 'other option'. Power Gem never OHKOing Ho-Oh, the primary target of Rock-type coverage prevents it from being a slash yet alone the recommended move.
Power Gem having a stronger hit against Yveltal is nice, but not at the cost of the core purpose of the set which is to set Stealth Rock, threaten entry hazard removers to the largest possible degree, and get 1.5ish KOs before going down. Yveltal only runs Defog on its Choice Scarf set whilst the LO set has a 75% chance to OHKO with Sucker Punch. Power Gem is usable, but the only benefit is being better against Yveltal on paper which does not translate well in game. Including it would result in essentially writing a full analysis on how to accomodate it given the constraints it puts on the rest of the team as this set is primarily used in the early-game so it isn't reasonable to expect Ho-Oh to be chipped into Power Gem range.
That is an ask that would be too much of the most important sets in the metagame, yet alone one which is ultimately quite niche at the end of the day. It isn't a definite no, but the reasons presented are not convincing me that Power Gem should be included. This thread isn't the best place to have a long conversation on this topic, but for Power Gem to be included, and this is just as a mention, not a slash I'd want the following conditions met:
1. A more convincing argument that that the downsides of missing the OHKO on Ho-Oh is worth the tradeoff.
2. That the changes would be relatively short to incorporate (around a paragraph max) as the assumption is that Ultra Necrozma will be somewhat reliably dealing with Ho-Oh and this is reflected in the teammates recommended.
There are a fair analyses that don't mention usable moves in large part because it contradicts the core purpose of the strategy dex: to serve as a resource for newer players to provide information about the metagame and information overload results in very niche, but viable options being excluded. Bob is the head honcho for this section, but given I wrote this analysis, I figured I'd give my input as to why these changes should not be considered at this time. This isn't to say you can't find success using these suggestions, although I'd personally be skeptical.