Can I use two Boost Shake to evolve my Basic Pokemon to a Stage 1 and then evolve it again to a Stage 2?
Since Boost Shake ends your turn immediately after using it, you cannot use two of them in the same turn.
Source: TPCi Rules Team (2021-09-09)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH7_142
SWSH7_142