any water Pokemon can use dive
Most water Pokemon can learn dive.
Since dive is not a HM in firered you will have to trade a Pokemon to a friend that has ruby, sapphire or emerald then using that game use the HM Dive to teach the move Dive to that Pokemon trade it back so firered can have that Pokemon again it will still have Dive however you cannot use it to dive underwater.
You get the abilty to use the move Dive from Tate and Liza in Mossdeep and then you can teach your Pokemon to Dive! X3 POKEMON-1001
you can not, you can get a Pokemon that knows dive in battle but you cant use it outside of battle.
you need to use a water type pokemon and teach it dive or use action replay
Dive is not an HM in leafgreen however some Pokemon can learn it on there own, if you want to have a Pokemon with dive have the Pokemon that you want learn dive in ruby or sapphire or emerald then have them trade you it and now you can use dive but not outside of battle because its not an HM.
No. Dive is an HM in kanto, so you can't use it out of battle. Some Pokemon can learn dive with no Tms or HMs, but you can't use it as a field move.
When you Surf, you will see dark spots in the sea. You can then use Dive, and go underwater.