Well, you can outpace slow Magnezones, slow Rotom-Ws, slow Brelooms and slow Heatrans.
Magnezones are pretty simple; either they are Modest and slow (they are faster than CB-Scizor usually) or Timid and faster than Scizor. With 216 EVs you will be outspeed Modest 252 Magnezone, but they usually don't go that far anyway unless they are Timid.
Against Brelooms, again, they dictate who goes first. Most of them have 252, so you won't be able to outpace them while it is likely that you beat the slow ones.
Heatrans are a pain because they are the lead of the speed creep. You need 100 plus the amount of speed Heatran has in order to outspeed it.
Honorable mention to Xatu, but this one does not need much speed to outpace any Adamant Scizor and survive a +2 Bullet Punch while it retaliates with Heat Wave.
All in all it is not recommended to save in speed when your foes have the bigger stick. It is the god stat.