Marshadow-GX not copying copying attack of pokemon discarded from Sudowoodo's ability

[freezekent]

Starting off, I forgot to copy the game log....so this is mostly to see if others have encountered this issue.

 

Situation in expanded: My opponent has roadblock Sudowoodo in play.  Their Silent Lab is in play.  My jolteon-ex is active.

 

My Marshadow-GX is benched.

 

I retreat jolteon-ex, and have a full bench (five on the bench).

 

I play sky field stadium, so now basic pokemon have abilities.  My opponent's sudowoodo's ability activates, so I can only have 4 bench pokemon.  I discard the jolteon-ex.

 

Marshadow has rainbow energy + double colorless attached.  I want to copy Jolteon-ex's attack "swift ray" now that it is in the discard.  That option isn't there (can pick any other attack from my toolbox).  I SWEAR it wasn't there.