Question

What order do things like poison/burn damage, leftovers/black sludge healing, hail/sandstorm damage or anything else like solar power damage go in?
Is there a specific order for these or is it just random?

Answer 1

• Weather: +6 [Sand, Hail]
• Items (Damaging): +5 [Sticky Barb, Black Sludge] This does not include Life Orb, which is recoiled after your move.
• Status: +4 [Burn, Poison] Confusion doesn't count.
• Items (Healing): +3 [Leftovers, Black Sludge]
• Abilities: +2 [Solar Power, Poison Heal, Rain Dish]
• Moves (Damaging): +1 [Fire Spin, Leech Seed]
• Moves (Healing): Normal [Aqua Ring, Ingrain]

Source