Sadly for Gardevoir, both Steel type moves and Fire type moves are not very effective against Salazzle, as both are resisted by fire types.

gardevoir survives one sludge bomb from timid salazzle if she has at least 4 points in the special defence, so she has the chance to survive and destroy the salazzle with psychic type move, too bad she opted for nonstab shotgun shot, that is not effective against salazzle at all.
Also it doesn't look like she has scarf or sash, or a berry (probably her item slot is occupied by a shotgun) so by using shotgun she basically screwed herself, that is if she's the samish level as salazzle, and if salazzle's trainer taught her sludge bomb, and will have enough knowledge to use it,