If your Pokémon has been Smokescreened on the previous turn, and you choose an attack that requires you to do something (such as discarding Energy) in order to use the Attack, do you pay the attack costs before you flip for the Smokescreen Effect?
Yes before, you still attempt the attack; the Smokescreen might just stop it from having any effect.
Source: WotC Chat (2000-04-13), WotC Chat (2001-04-05)

Relevant cards

Note: All applicable cards may not be listed below.
COL1_60
HGSS1_70
PL3_65