Atk: Yungoos and Pikipek in daytime on Route 1 (combined 40% encounter) or Spinarak, Pikipek and Rattata-A at night on Route 1 (combined 60% encounter) or Lillipup and Mudbray on Paniola Ranch (combined 60% encounter).
Spe: I used to use Cutiefly in Melemele Meadow (30% encounter) but that's now 20% in USUM. Much easier from the outset would be to just step outside to Route 3 - Cutiefly and Spearow for a 60% combined encounter in SMUSUM (now I feel stupid as hell). Also the scripted flying encounters on the rocky area in Route 3 yields 70% for Spearow. (Edit: Verdant Cavern offers 100% encounter for Speed EVs - Noibat, Zubat and Diglett-A. Thanks to
Detective Barricade for bringing that up)
There are probably other, equally valid locations, but I hope this may be of help.