Ruling Having your pokemon knocked out before the start of your turn.

[Cococo]

This question has always been bugging me and I've never seen it explained clearly in any rulebook.
Assuming you already have pokemon on your bench, when your opponent knocks out your active pokemon do you absolutely have to bring up one of your benched before you draw a card or is it alright to assign an active pokemon just when you are ready to attack?

(For example would it be ok to have your active position empty during your turn while you use a trainer to add more pokemon to the bench and bring up one of those up instead of the pokemon you had on your bench at the time your active pokemon got knocked out?)

 

[RB Golbat]

When the active Pokemon is knocked out, you must immediately replace it before you do anything else.

 

[DNA]

There is never an instance where you do not have an Active Pokemon. If the Active Pokemon is Knocked Out, it is replaced immediately before continuing with the game.

 

[PMJ]

Just to clarify, in real life there is obviously a time in which you have no Active, but in game time, that doesn't exist. As far as the game is concerned, it's an instantaneous change. If you can't make that change, you lose.