Can I use Heavy Ball to search for Wimpod that has the "Wimp Out" Ability on my first turn?
Yes, you can. Abilities only work when in play (unless the card says otherwise), so Wimp Out is not active while Wimpod is still in the deck.
Source: TPCi Rules Team (2017-09-14)

Relevant cards

Note: All applicable cards may not be listed below.
SM3_16
SMA_SV4
SMA_SV4