When I try to attack, does Marowak's "Bodyguard" Ability prevent me from having to flip a coin if my active Pokemon was attacked last turn with Silicobra's "Sand Attack"?
The effect of Sand Attack is on your Pokemon that was attacked, not on you. So, Bodyguard does not prevent you from having to flip a coin to see if the attack goes through
Source: TPCi Rules Team (2022-10-13)

Relevant cards

Note: All applicable cards may not be listed below.
XY10_37
SWSH1_107
SWSH1_107