Does Bright look have to switch

[The Ralts]

Luxray GL lv. X reads: "Once during your turn (before your attack) when you put luxray LV. X from your hand onto your active Luxray GL, you MAY switch the defending pokemon with one of your opponent's benched pokemon."
So if you lvl up luxray GL, and announce bright look, can you leave their current pokemon active?

 

[PokePop]

You don't have to use Bright Look.
When you Level Up, don't declare the Power.

However, if you do declare it, then you do have to switch a Pokemon.

That goes for all "when you play ... from your hand" Powers, you know.

If you don't declare the use, it's not used.