This is an amalgamation of all the Speed benchmarks relevant to the 1v1 metagame. They are organized from slowest to fastest. Speeds defaulted as the highest Speed possible given the Pokemon's most common nature/s, with slow Speed (0 EVs) only being included if a large amount of spreads (about 20% or more) run 0 Speed EVs. This is to show the fastest possible Speed a Pokemon will realistically attain, so that one may teambuild as safely as possible. Speed creeping for a 'standard set' is not reliable in the long run, and 'optimal' sets will change constantly, and your opponent can often shift their EVs to suddenly beat you. Relevant benchmarks needed to outspeed certain Speed tiers/Pokemon after a boost are also included. For reference's sake, this is the key used for the 1v1 Speed Tiers (based on Rosa's speed tier key):

Key
Min Speed = 0 IVs + Reducing Nature + 0 EVs
-Nature = Reducing Nature + 0 EVs
Bulky = 0 EVs
Fast = 252 EVs
Max Speed = Increasing Nature + 252 EVs
Any instance of a Speed increasing item, ability, or relevant element will also be mentioned.

Bolded text will be used to indicate particularly important benchmarks

Speed Tiers

40: Min Speed Ferrothorn, Min Speed Escavalier
46: Bulky Pyukumuku
56: Min Speed Aromatisse
76: Bulky Ferrothorn, Min Speed Rhyperior, Bulky Escavalier
86: -Nature Slowbro-Galar
92: Bulky Avalugg
94: Min Speed Aggron, Min Speed Diancie
96: Bulky Glastrier, Bulky Corsola-Galar, Bulky Slowking-Galar, Bulky Steelix, Bulky Reuniclus, Bulky Slowbro-Galar
106: Bulky Quagsire, Bulky Toxapex
112: Min Speed Aegislash
114: Bulky Gastrodon
116: Bulky Rhyperior, Bulky Golisopod
122: -Nature Diancie
126: Bulky Crustle, Bulky Conkeldurr, Bulky Marowak-A
136: Bulky Azumarill, Bulky Aggron, Bulky Registeel, Bulky Diancie, Bulky Chansey, Bulky Regice, Bulky Regirock
140: -Nature Swampert
142: -Nature Celesteela
146: Bulky Blissey
154: Bulky Type: Null
156: Bulky Sylveon, Bulky Primarina, Bulky Clefable, Bulky Incineroar, Bulky Magnezone, Bulky Swampert, Bulky Grimmsnarl, Bulky Porygon2, Bulky Jellicent
158: Bulky Celesteela, -Nature Metagross, Bulky Tyranitar,
159: Fast Steelix
163: Fast Carracosta
166: Bulky Scizor
170: Bulky Corviknight
176: Bulky Volcanion, Bulky Metagross, Bulky Skarmory
179: Max Speed Carracosta, Fast Rhyperior
186: Bulky Tapu Bulu, Bulky Dracozolt, Bulky Dracovish
189: Fast Crustle, Fast Conkeldurr
190: Bulky Heatran
192: Bulky Blastoise
194: Bulky Buzzwole
196: Bulky Togekiss, Bulky Regidrago, Bulky Goodra, Bulky Chandelure, Bulky Mamoswine
198: Bulky Gyarados
199: Fast Azumarill, Fast Aggron, Fast Regice
206: Bulky Tapu Fini, Bulky Cresselia, Bulky Rillaboom, Bulky Sawk, Bulky Suicune, Bulky Kommo-o
208: Bulky Rotom-A
209: Fast Blissey
216: Bulky Moltres-Galar, Bulky Moltres
218: Bulky Landorus-T
219: Fast Sylveon, Fast Primarina, Fast Incineroar, Fast Magnezone, Fast Clefable, Fast Jellicent
220: Bulky Krookodile
224: Bulky Raboot
226: Bulky Tapu Lele, Bulky Zygarde-50%, Bulky Arcanine, Bulky Kyurem, Bulky Silvally
229: Max Speed Blissey
230: Bulky Urshifu-S, Bulky Urshifu-R
231: +1 Bulky Type: Null
233: Fast Corviknight
236: Bulky Entei, Bulky Volcarona, Bulky Zapdos, Bulky Zapdos-G
239: Fast Volcanion, Fast Metagross, Fast Skarmory
240: Max Speed Sylveon, Max Speed Primarina, Max Speed Magnezone, Bulky Garchomp, Max Speed Jellicent, Max Speed Clefable
243: Max Speed Celesteela
249: Fast Tapu Bulu, Fast Dracozolt, Fast Dracovish, Fast Toxtricity
253: Fast Heatran
255: Fast Diggersby, Fast Blastoise
259: Fast Togekiss, Fast Regidrago, Fast Blaziken, Fast Chandelure, Fast Mamoswine
261: Fast Gyarados
262: Max Speed Metagross
268: Bulky Whimsicott
269: Fast Tapu Fini, Fast Rillaboom, Fast Sawk, Fast Suicune, Fast Kommo-o, Fast Nidoking
271: Fast Rotom-A
273: Max Speed Dracovish, Max Speed Dracozolt
275: Fast Excadrill
278: Max Speed Heatran
279: Fast Porygon-Z, Fast Moltres
280: Max Speed Diggersby, Max Speed Blastoise
281: Fast Landorus-T
283: Fast Krookodile
284: Max Speed Togekiss, Max Speed Blaziken, Max Speed Gardevoir, Max Speed Venusaur, Max Speed Chandelure
287: Max Speed Gyarados, Fast Raboot
288: Bulky Talonflame
289: Fast Darmanitan-G, Fast Tapu Lele, Fast Arcanine, Fast Kyurem, Fast Zygarde-50%, Fast Darmanitan, Fast Silvally
291: Fast Togedemaru
293: Fast Urshifu-S, Fast Urshifu-R, Fast Haxorus
294: +1 Bulky Regidrago
295: Max Speed Rillaboom, Max Speed Sawk, Max Speed Suicune, Fast Hydreigon, Max Speed Nidoking
297: +1 Bulky Gyarados
298: Max Speed Rotom-A
299: Fast Volcarona, Fast Entei, Fast Zapdos, Fast Zapdos-G, Fast Salamence, Fast Ninetales
302: Max Speed Excadrill
303: Fast Garchomp
306: Max Speed Porygon-Z, Max Speed Roserade, Max Speed Moltres
308: +2 Bulky Type: Null
309: Max Speed Landorus-Therian
313: Fast Blacephalon
315: Fast Keldeo
317: Max Speed Darmanitan-G, Max Speed Tapu Lele, Max Speed Kyurem, Max Speed Darmanitan, Fast Durant, Max Speed Zygarde-50%, Max Speed Silvally
319: Fast Gengar, Fast Latios
320: Max Speed Togedemaru
322: Max Speed Urshifu-S, Max Speed Urshifu-R, Max Speed Haxorus
324: Max Speed Hydreigon
326: +2 Fast Carracosta
328: Max Speed Entei, Max Speed Volcarona, Max Speed Zapdos, Max Speed Zapdos-G, Max Speed Ninetales, Max Speed Salamence, Max Speed Celebi, Scarf Fast Clefable, Scarf Fast Jellicent
331: Max Speed Landorus, Max Speed Thundurus-T
333: Max Speed Garchomp, Fast Salazzle
335: Max Speed Nihilego
339: Max Speed Zarude
341: Fast Naganadel
344: Max Speed Blacephalon
346: Max Speed Keldeo, Max Speed Terrakion
348: Max Speed Kartana, Max Speed Durant, Max Speed Ninetales-A
349: Fast Weavile
350: Max Speed Archeops, Max Speed Gengar, Max Speed Latios
351: Fast Talonflame
354: +1 Bulky Volcarona
358: Fast Scarf Metagross, Fast Scarf Volcanion, +2 Max Speed Carracosta
359: Fast Spectrier, Fast Tapu Koko
360: Scarf Max Speed Clefable, Scarf Max Speed Jellicent
361: Max Speed Raikou
366: Max Speed Salazzle
369: Fast Darmanitan-Galar-Zen.
373: Scarf Fast Dracozolt, Scarf Fast Dracovish
375: Max Speed Naganadel
378: +2 Fast Crustle
379: Fast Scarf Heatran
382: Scarf Fast Diggersby
383: Fast Dragapult, Max Speed Weavile
384: +2 Bulky Blastoise
385: Fast Zeraora, +3 Bulky Type: Null
386: Max Speed Talonflame
388: +1 Fast Regidrago, +1 Fast Blaziken, Scarf Fast Chandelure
391: +1 Fast Gyarados
394: Max Speed Spectrier, Max Speed Tapu Koko
403: Scarf Fast Cresselia, Scarf Fast Nidoking
406: Scarf Fast Rotom-A
409: Scarf Max Speed Dracovish, Scarf Max Speed Dracozolt
412: Scarf Fast Excadrill
414: +2 Max Speed Crustle
417: Scarf Max Speed Heatran
418: Scarf Fast Porygon-Z
420: Scarf Max Speed Diggersby
421: Max Speed Dragapult
423: Max Speed Zeraora
426: Scarf Max Speed Togekiss, +1 Max Speed Regidrago, +1 Max Speed Blaziken, Scarf Max Speed Gardevoir, Scarf Max Speed Chandelure
427: +1 Fast Zygarde-50%
430: +1 Max Speed Gyarados
433: Scarf Fast Darmanitan-Galar, Scarf Fast Tapu Lele, Scarf Fast Kyurem,
441: Max Speed Pheromosa
442: Scarf Max Speed Tapu Fini, Scarf Max Speed Cresselia, Scarf Max Speed Sawk, Scarf Max Speed Nidoking
447: Scarf Max Speed Rotom-A
448: +1 Fast Volcarona
453: Scarf Max Speed Excadrill
459: Scarf Max Speed Porygon-Z
469: Scarf Fast Blacephalon
472: +2 Bulky Zapdos
475: Scarf Max Speed Darmanitan-Galar, Scarf Max Speed Tapu Lele, Scarf Max Speed Kyurem, Scarf Max Speed Darmanitan
478: Scarf Fast Gengar, Scarf Fast Latios
483: Scarf Max Speed Urshifu-S, Scarf Max Speed Haxorus
492: +1 Max Speed Volcarona, Scarf Max Speed Salamence, Scarf Max Speed Celebi
498: +2 Fast Toxtricity
499: Scarf Max Speed Garchomp, Fast Regieleki
510: +2 Fast Blastoise
511: Scarf Fast Naganadel
516: Scarf Max Speed Blacephalon
522: Scarf Max Speed Kartana
525: Scarf Max Speed Archeops, Scarf Max Speed Gengar, Scarf Max Speed Latios
553: +1 Fast Darmanitan-Galar-Zen
560: +2 Max Speed Blastoise
562: Scarf Max Speed Naganadel
598: +2 Fast Zapdos

Speed Benchmarks
125: Speed at which Modest Regieleki's Electro Ball moves from 150 BP to 120 BP
167: Speed at which Modest Regieleki's Electro Ball moves from 120 BP to 80 BP.

190: Speed to outspeed Max Speed Togekiss and Gardevoir when you're at +1 (285)
220: Speed to outspeed Entei when you're at +1 (320)
281: Speed to outspeed Dragapult when they’re at -1 (280)
282: Speed to outspeed Dragapult when you’re at +1 (423)
283: Speed to outspeed Zeraora when you're at +1 or they're at -1 (424 and 282)
334: Speed to outspeed Fast Regieleki when you're at +1 (501)


If you have any suggestions for additions or removals of Speed stats, feel free to respond to this thread in a constructive manner. Please suggest Speeds that are relevant to the 1v1 metagame, backed up by substantial reasoning, at the time of your posting. Thank you!