Wait, whut?
Sigilyph doesn't care about its weaknesses because it can actually take a hit and OHKO or 2HKO whatever is targetting them (except maybe Emolga, but that's a whole other megillah with Double Team and getting outrun). Most of the game's Crunches are unSTABbed and those that are should not be fought off with Sigilyph. Sigilyph may not have the widest of movepools, but it really doesn't matter - Psybeam/Psychic and Air Cutter/Air Slash are all it needs to take out the things that it can feasibly take out. You have five other party spaces to handle things such as the Sandile and Scraggy lines or the Roggenrola line.
Sigilyph doesn't care about its weaknesses because it can actually take a hit and OHKO or 2HKO whatever is targetting them (except maybe Emolga, but that's a whole other megillah with Double Team and getting outrun). Most of the game's Crunches are unSTABbed and those that are should not be fought off with Sigilyph. Sigilyph may not have the widest of movepools, but it really doesn't matter - Psybeam/Psychic and Air Cutter/Air Slash are all it needs to take out the things that it can feasibly take out. You have five other party spaces to handle things such as the Sandile and Scraggy lines or the Roggenrola line.