Go to one island and find the ember spa there is an old man in there in a corner he has HM6
Defog did not become a move until Generation 6 so you will not be able to find it in LeafGreen
No its not an HM in leafgreen.
The HM's that are in leafgreen are: Cut, Fly, Surf, Strength, Flash, Rock Smash, Waterfall.
There's no Dive HM on Pokemon Leaf Green.
On route 16.
you cant
In icefall cave.
You cannot get HM Dive in Pokémon LeafGreen.Since Dive is not an HM in leafgreen the only way to get one of your Pokemon to learn Dive is to trade it to ruby, sapphire or emerald then teach it Dive using the HM then trade it back to leafgreen.
HM03 is surf
you get it in the captains quarters.
There isn't one
Icefall cave.