If I use Pokemon Communication to put a Pokemon into my deck, am I allowed to voluntarily fail and choose to take no Pokemon out of my deck?
The contents of your deck is not public knowledge so the deck search can fail, even if you've just put a Pokemon into the deck.
Source: PUI Rules Team (2010-02-04)

Relevant cards

Note: All applicable cards may not be listed below.
BW1_99
HGSS1_98