Nominating scarf hoopa to b+.
Hoopa-u as top tier scarf is joke!
1. Fighting, dark, psychic are common resistances what makes it hard to clean up. There are a lot offensive dart types, psychic is very mediocre STAB (a lot some 4x resistances, some immunities, a lot 2x resistances) and coverage options aren't that good when you are choice locked. In comparison to quick EQ it's coverage is quite disappointing.
2. Loses to MOST priority user. People complain about drill losing to both azu and loom. Let's look at hoopa
252+ Atk Life Orb Technician Breloom Mach Punch vs. 0 HP / 0- Def Hoopa Unbound: 235-278 (78 - 92.3%) -- 31.3% chance to OHKO after Stealth Rock
252+ Atk Choice Band Huge Power Azumarill Aqua Jet vs. 0 HP / 0- Def Hoopa Unbound: 201-237 (66.7 - 78.7%) -- guaranteed 2HKO after Stealth Rock
252 Atk Sharp Beak Talonflame Brave Bird vs. 0 HP / 0- Def Hoopa Unbound: 288-340 (95.6 - 112.9%) -- guaranteed OHKO after Stealth Rock
252 Atk Life Orb Bisharp Sucker Punch vs. 0 HP / 0- Def Hoopa Unbound: 278-329 (92.3 - 109.3%) -- guaranteed OHKO after Stealth Rock
252+ Atk Choice Band Dragonite Extreme Speed vs. 0 HP / 0- Def Hoopa Unbound: 247-291 (82 - 96.6%) -- 62.5% chance to OHKO after Stealth Rock
252+ Atk Aerilate Mega Pinsir Quick Attack vs. 0 HP / 0- Def Hoopa Unbound: 180-213 (59.8 - 70.7%) -- guaranteed 2HKO after Stealth Rock
44 Atk Technician Mega Scizor Bullet Punch vs. 0 HP / 0- Def Hoopa Unbound: 160-189 (53.1 - 62.7%) -- guaranteed 2HKO after Stealth Rock
However bulky mega scizor has enough meat to take 3 hits from scarf hoopa u. Offensive SD still takes one and sets up SD.
Garchomp, Lando, Jirachi and even Drill are much more durable against priority.
3. Is SLOW!
Few quicekr mega mons like Zam, Aerodactyl, Sceptile are quicker and that's quiet bad impying you are supposed to be the fastest mon on the field. It is also slower than most scarfs like Lando, Drill, Garchomp, Lati, Jirachi or Keldeo. But that's not the end, scarf hoopa is slower than ZardX and Gyarados at +1! It is quicker than dragonite at +1 so you can reliably... Wait, dragonite has Espeed.
4. Has very little utility beside being fast.
Lando has intimidate plus utrun making it great pivot, Jirachi flinches everything, has trick, healing wish, utrun and good defensive typing. Drill... Well it can spin it is something! Also with mold breaker it's stab is resisted by even smaller number of mons. Keldeo is overall quiet bulky, has exelent typing and burns.
What has hoopa? Some special bulk but not really, and poor psychic immunity. And 4x weakness to u-turn making it u-turn folder for scarf jirachi/lando.
I cannot see any excuse to put scarf Hoopa over both Lando and Jirachi!