Can I use Wally or Evosoda on a Snorlax to search my deck, even though there is {currently} no evolution of Snorlax?
No, there has to at least be the possibility of a valid evolution in order to use this card. Sorry.
Source: TPCi Rules Team (2018-07-26)

Relevant cards

Note: All applicable cards may not be listed below.
XY1_116
XY6_107
XY6_94