Somebody correct me if I'm wrong with the following calcs, because I would rather have than than realize just how overpowered Alola-Raichu--or rather, speed boosting abilities in general--is. Wall of text incoming.
According to calculations, a 110 base stat doubled (due to Surge Surfer) results in a total base stat of 247; that is, naturally, without counting EVs or nature. Slap a positive nature and some few EVs (let's use 80, as it's enough to outspeed an unchoiced Excadrill under sand) and we end up with a total of 605 in its highest stat. It means that, after a Choice Scarf, this reaches 907, and after one single Agility, this skyrockets up to 1210. Not even a Manaphy, under normal circumstances, would reach that much SpA after one Tail Glow.
And then, the damage calcs, with Life Orb. I will not use Hazards for these calculations. In order to to simulate its other stats, I have set its Attack and Speed to a base 255 with 236 EVs, reaching the value of 605:
80+ SpA Life Orb Raichu-Alola Thunderbolt vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 247-292 (38.4 - 45.4%) -- guaranteed 3HKO
80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 411-485 (64 - 75.5%) -- guaranteed 2HKO
236 Atk Life Orb Raichu-Alola Extreme Speed vs. 4 HP / 252+ Def Eviolite Chansey: 253-299 (39.4 - 46.5%) -- guaranteed 3HKO
Swapping the Life Orb out for a Choice Scarf, it goes up to 907, as mentioned. I have boosted Attack, Special Attack and Speed to +1 for the sake of the simulation:
+1 80+ SpA Raichu-Alola Thunderbolt vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 286-337 (44.5 - 52.4%) -- 21.5% chance to 2HKO
+1 80+ SpA Raichu-Alola Electro Ball (150 BP) vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 474-558 (73.8 - 86.9%) -- guaranteed 2HKO
+1 236 Atk Raichu-Alola Extreme Speed vs. 4 HP / 252+ Def Eviolite Chansey: 292-344 (45.4 - 53.5%) -- 41% chance to 2HKO
Swapping the Choice Scarf for, say, Life Orb again and then giving it an Agility Boost, I will increase all of the aforementioned stats to a +2 boost:
+2 80+ SpA Life Orb Raichu-Alola Thunderbolt vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 493-581 (76.7 - 90.4%) -- guaranteed 2HKO
+2 80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 4 HP / 252 SpD Eviolite Chansey in Electric Terrain: 820-967 (127.7 - 150.6%) -- guaranteed OHKO
+2 236 Atk Life Orb Raichu-Alola Extreme Speed vs. 4 HP / 252+ Def Eviolite Chansey: 506-595 (78.8 - 92.6%) -- guaranteed 2HKO
And there you have Raichu-A as the Pokémon that can not only oneshot a Chansey but also overkill it by a great margin. You can only ever respond to that with a sashed/Sturdy Pokémon, both of which go to waste if rocks are up. Potentially with a Scarfed Excadrill under sandstorm; as in, only if said Alola-Raichu is not scarfed or already boosted by Agility, or its Electric Terrain has ran out, but then chances are your team already has been tore up a gigantic hole. Otherwise, you can imagine how many times that Surf would kill it over.
Assault Vested Tyranitar can work if it's Life Orb or Choiced, but that requires said Tyranitar to be at least above half health:
80+ SpA Life Orb Raichu-Alola Thunderbolt vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 153-183 (37.9 - 45.4%) -- guaranteed 3HKO
80+ SpA Life Orb Raichu-Alola Electro Ball (120 BP) vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 208-246 (51.6 - 61%) -- guaranteed 2HKO
+1 80+ SpA Raichu-Alola Thunderbolt vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 178-211 (44.1 - 52.3%) -- 19.1% chance to 2HKO
+1 80+ SpA Raichu-Alola Electro Ball (150 BP) vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 297-351 (73.6 - 87%) -- guaranteed 2HKO
+2 outright kills it:
+2 80+ SpA Life Orb Raichu-Alola Thunderbolt vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 308-364 (76.4 - 90.3%) -- guaranteed 2HKO
+2 80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 248 HP / 252+ SpD Assault Vest Tyranitar: 516-608 (128 - 150.8%) -- guaranteed OHKO
Other Tapus can stop the murder train, but that also depends on the circumstance:
80+ SpA Life Orb Raichu-Alola Electro Ball (120 BP) vs. 252 HP / 252+ SpD Assault Vest Tapu Bulu: 107-126 (31.1 - 36.6%) -- guaranteed 4HKO after Grassy Terrain recovery
236 Atk Life Orb Raichu-Alola Extreme Speed vs. 252 HP / 0 Def Tapu Bulu: 169-200 (49.1 - 58.1%) -- 62.9% chance to 2HKO after Grassy Terrain recovery
+1 80+ SpA Raichu-Alola Electro Ball (150 BP) vs. 252 HP / 252+ SpD Assault Vest Tapu Bulu: 153-181 (44.4 - 52.6%) -- guaranteed 3HKO after Grassy Terrain recovery
+1 236 Atk Raichu-Alola Extreme Speed vs. 252 HP / 0 Def Tapu Bulu: 196-231 (56.9 - 67.1%) -- guaranteed 2HKO after Grassy Terrain recovery
+2 80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 252 HP / 252+ SpD Assault Vest Tapu Bulu: 265-313 (77 - 90.9%) -- guaranteed 2HKO after Grassy Terrain recovery
+2 236 Atk Life Orb Raichu-Alola Extreme Speed vs. 252 HP / 0 Def Tapu Bulu: 338-399 (98.2 - 115.9%) -- 87.5% chance to OHKO
80+ SpA Life Orb Raichu-Alola Electro Ball (80 BP) vs. 0 HP / 252+ SpD Assault Vest Tapu Lele: 126-149 (44.8 - 53%) -- 29.7% chance to 2HKO
+1 80+ SpA Raichu-Alola Electro Ball (120 BP) vs. 0 HP / 252+ SpD Assault Vest Tapu Lele: 216-255 (76.8 - 90.7%) -- guaranteed 2HKO
+2 80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 0 HP / 252+ SpD Assault Vest Tapu Lele: 468-551 (166.5 - 196%) -- guaranteed OHKO
80+ SpA Life Orb Raichu-Alola Electro Ball (80 BP) vs. 248 HP / 252+ SpD Assault Vest Tapu Fini: 229-273 (66.7 - 79.5%) -- guaranteed 2HKO
236 Atk Life Orb Raichu-Alola Extreme Speed vs. 248 HP / 192 Def Tapu Fini: 144-170 (41.9 - 49.5%) -- guaranteed 3HKO
While Fini is able to take an Electro Ball to the face, as long as it's not boosted, one Choice Scarf proves to be more than enough to oneshot it:
+1 80+ SpA Raichu-Alola Electro Ball (150 BP) vs. 248 HP / 252+ SpD Assault Vest Tapu Fini: 494-584 (144 - 170.2%) -- guaranteed OHKO
+2 80+ SpA Life Orb Raichu-Alola Electro Ball (150 BP) vs. 248 HP / 252+ SpD Assault Vest Tapu Fini: 858-1009 (250.1 - 294.1%) -- guaranteed OHKO
I believe this should suffice to prove how not only Alola-Raichu but essentially anything that has access to speed boosting abilities can turn out to be merciless and often gives you no answer other than to somehow abuse of those same broken settings. Or, dunno, forfeit.
I'm aware it has been mentioned time and time again that those abilities are broken in this meta, I just took the effort to calculate how destructive one of them can be.
Just a question, is that calc the equivalent of max Speed on Raichu inside Electric Terrain?