Darkness Reduces evasion by 20%. Dark and Ghost types are unaffected. All Dark type moves are guaranteed to hit. (Tbh, only 3 Dark type moves have less than 100 accuracy: Dark Void, Night Daze and Snarl.) Psychic types lose 20% defense/special defense.
Morning Sun and Synthesis heal 1/8th. Moonlight heals 1/3. Thunder and Hurricane have their Accuracy reduced to 50% (60% after evasion drop). Solar Beam takes 2 turns to charge, striking on the third. Solar Power users suffer their health loss, with no power gain.