If your Pokemon holds a Lagging Tail,it will be slower,
so usually the foe attacks first.
Revenge and Payback will cause double damage if you move last.
Use Trick or Switcheroo on the foe,then you can swap items,making the foe slower,which also powers up Gyro Ball.
And using Flail will do A LOT of damage if the foe attacks
really hard,if your Pokemon manages to hang in there.
There are good things to do with the Lagging Tail,even though it reduces speed.