After commands are chosen for the round, the game determines the turn order of Pokemon, whereby each Pokemon's Speed is calculated. It's not the case that a Pokemon's Speed is fixed each round, but rather (most of the time) its turn order.
My description for Zoom Lens reads: "Accuracy of attacks by the holder is multiplied by 1.2 if holder strikes last this round or if the attack is Future Sight or Doom Desire." Zoom Lens, therefore, is not affected by the Speed of a Pokemon, but only whether a Pokemon is last in the turn order. After You and Quash both affect the turn order of Pokemon, not their Speed.
With After You, if a Pokemon that would otherwise strike last is moved earlier in the turn order, Zoom Lens would fail to work for that Pokemon that round. After You, however, "[f]ails if ... opponent would already strike immediately after the user this round": After You can't make a Pokemon strike last it wouldn't already do so.
With Quash, on the other hand, the Pokemon affected by Quash will indeed receive the accuracy boost from Zoom Lens if it goes last in the turn order this way.
The effect of Lock-On (and Mind Reader) will end even when either the user or opponent uses Baton Pass.
I've done in-game tests to make sure of all of the above.
Last edited by poccil; Jun 15th, 2011 at 2:44:29 AM.