Can I use Porygon-Z's "Crazy Code" Ability to attach Impact Energy to a Pokemon that isn't a Single Strike Pokemon?
Yes you can, but then it would get discarded immediately. However, if that Pokemon was Poisoned, Impact Energy would remove the Special Condition.
Source: TPCi Rules Team (2021-07-01)

Relevant cards

Note: All applicable cards may not be listed below.
SM10_157
SM10_157
SWSH6_157
SWSH6_157