Just going to respond to your pointsWhen considering Hoopa-U's Scarf set, the thing that appeals to me about it is how stupidly easy it is to just click a move and expect things to die, even against bulkier offensive mons.
252 Atk Hoopa-Unbound Hyperspace Fury vs. 144 HP / 0 Def Mega Charizard X: 175-207 (52.5 - 62.1%) -- guaranteed 2HKO
252 SpA Keldeo Scald vs. 144 HP / 0 SpD Mega Charizard X: 150-177 (45 - 53.1%) -- 28.9% chance to 2HKO
That's a noteworthy power difference over Keldeo, using what is each's most spammable move (Hydro Pump hits harder, but Keldeo's main move would be Scald to burn through checks and counters). This is not Keldeo's preferred set, but OU on the whole is moving from Scarfers to priority and mons naturally fast enough to hit that level with things like Weavile, Torn-T, Manectric, and Alakazam, to name a few. Hoopa lacks the issue Scarfers often run into of locking itself into an exploitable move. The lack of significant Dark Resists in OU reduces that issue for Hoopa significantly, leaving only Fairies, of which Clefable, the most defensive one. is not going on offense where it can eat HF without worrying over Gunk shot. Offense in general doesn't have too many Pokemon with the natural bulk to eat Hoopa's moves. Hoopa is less prone to exploitation once it picks a STAB.
Okay, issues I take with this replay.
1. You say Mawile was a non-factor, but it basically killed Azumarill in the opening turns. If you mean on Hoopa's effect on the battle, fine. That said, Mawile took the Mega Slot, which using a different mon for could have made the battle go significantly differently, possibly reworking much of the team. Mawile didn't impact the battle immensely, but it obviously had a huge influence in the teambuilding for the Mega slot alone.
2. Alakzam was brought in on a free switch from a Sac, something Hoopa could just as easily do to Wallbreak. Heck, he could have just as easily brought it in on the Psychic you used to beat Garchomp. Hoopa has problems switching in, but so do a lot of high ranked mons like Weavile and Gengar. That said, Hoopa at least has the bulk to switch into Special Attacks, and in general is dealing with less direct attacking against the bulky builds it's used for.
3. Alakazam having Signal Beam is either giving up coverage or the Utility of its 4th moveslot, which Alakazam needs to perform well against bulky/stall teams that can stomach his power. If it was to lure Hoopa, why are you luring something that should be easy to RK anyway? Maybe because surviving this
252 SpA Mega Alakazam Focus Blast vs. 0 HP / 0 SpD Hoopa-Unbound: 130-154 (43.1 - 51.1%) -- 5.5% chance to 2HKO
Means Hoopa wins, forces Mega Zam out, and gets to smack something otherwise. Alakazam had to be tailored to beat it to avoid losing momentum, which if anything seems an example of Hoopa's influence on the Meta if Mega Alakazam is giving up a moveslot for a move that is less effective against anything but Hoopa.
Luring by definition is reducing overall effectiveness to draw in and beat a mon for teammates. A mon is not worth luring if it doesn't cause problems for your team, which in the replay was offensive, the style Hoopa fares worst against.
Hoopa has the raw power and the movepool to basically ensure that the second it gets on the field, it will MURDER something.
1.Meant it in terms of hoopa u of course a different mega could make a different team, this replay was just to show how bad hoopa u is against offense
2. Hoopa u DID get a free switch and it got forced out, with its 80 base speed its not hitting anything if its not scarf..... I ran signal beam before hoopa u came out and Im running it now because hoopa u is currently a soft check to mega alakazam and running signal beam which has better coverage than sball anyway (not like jirachi wishmaker gets 2 hit koed by sball anyway...) so if i can kill a soft check without that much of a downside why wouldn't I...
as someone posted above hoopa u just has to many CRIPPLING flaws to be a plus rank..... especially in this meta where things like azumarill, keldeo, mega scizor, and manaphy are a plus rank
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