Here's an idea I've been tooling around with for a little while: typed damage for everything.
The premise is this: You know how Stealth Rock does Rock-type damage? What if everything like that did typed damage? Burns dealing Fire-type damage, Hail dealing Ice-type damage, Spikes dealing Ground-type damage, the list goes on. I think it would certainly make people think about hazards and status effects more rather than just spraying them around with gay abandon.
Here is a full list of changes:-
Burn: Fire-type damage, 1/16th max HP per turn
Paralysis: Electric-type damage, 1/16th max HP per turn
Sleep: Psychic-type damage, 1/16th max HP per turn
Poison: Poison-type damage, 1/8th max HP per turn
Freeze: Ice-type damage, 1/16th max HP per turn
Bad Poison: Poison-type damage, stacking 1/16th max HP per turn
Leech Seed: Grass-type damage, 1/8th max HP per turn, heals user for amount of damage dealt
Flinch: Dark-type damage, 1/8th max HP per turn
Confusion: Psychic-type damage, as normally calculated
Binding: Deals damage according to the type of the move used, 1/8th max HP per turn, increased to 1/6th max HP if user is holding a Binding Band
Can't Escape: Deals damage according to the type of the move used, 1/16th max HP per turn
Fairy Lock: Fairy-type damage, 1/8th max HP per turn
Curse: Ghost-type damage, 1/4th max HP per turn, cannot KO
Embargo: Dark-type damage, 1/16th max HP per turn
Encore: Normal-type damage, 1/16th max HP per turn
Heal Block: Psychic-type damage, 1/16th max HP per turn
Identified: Psychic-type damage, 1/16th max HP per turn
Infatuation: Fairy-type damage, 1/16th max HP per turn
Nightmare: Dark-type damage, 1/4th max HP per turn, only affects Sleeping targets
Taunt: Dark-type damage, 1/16th max HP per turn
Telekinesis: Psychic-type damage, 1/8th max HP per turn
Torment: Dark-type damage, 1/16th max HP per turn
Spikes: Ground-type damage, 1/8th max HP upon entry, increased to 1/6th max HP if two layers are active and 1/4th max HP if 3 layers are active.
Toxic Spikes: Poison-type damage, 1/16th max HP and inflicts Poison upon entry, increased to 1/8th max HP and inflicts Bad Poison if two layers are active
Sticky Web: Bug-type damage, -1 Speed stage upon entry, 1/16th max HP per turn
Harsh Sunlight: Fire-type damage, 1/16th max HP per turn, all Pokémon on field
Extremely Harsh Sunlight: Fire-type damage, 1/8th max HP per turn, all, all Pokémon on field
Rain: Water-type damage, 1/16th max HP per turn, all Pokémon on field
Heavy Rain: Water-type damage, 1/8th max HP per turn, all Pokémon on field
Sandstorm: Rock-type damage, 1/16th max HP per turn, all Pokémon on field
Hail/Diamond Dust: Ice-type damage, 1/16th max HP per turn, all Pokémon on field
Mysterious Air Current: Flying-type damage, 1/16th max HP per turn, all Pokémon on field
Misty Terrain: Fairy-type damage, 1/16th max HP per turn, all grounded Pokémon, Fairy-types immune
Grassy Terrain: Grass-type damage, 1/16th max HP per turn, all grounded Pokémon, Grass-types immune
Electric Terrain: Electric-type damage, 1/16th max HP per turn, all grounded Pokémon, Electric-types immune
Psychic Terrain: Psychic-type damage, 1/16th max HP per turn, all grounded Pokémon, Psychic-types immune
Thoughts?