no, because some forms are only avalibe in diamond, pearl, platinum...........etc
Here are all the pokemon that evolve by water stone: Lombre, Evee, Staryu, Shellder.
Trade it to ruby,sapphire or emerald have them evolve your evee at night then give it back to leafgreen.
No because there is no clock in leafgreen you must trade evee to a game with an internal clock to make it evolve to evee those games are ruby, sapphire and emerald also heartgold, soulsilver, diamond, pearl and platinum.
If you breed a evee you will get an egg when it hatches it will be evee this is a great way to get all the forms of evee.
Evee can be obtained only from firered and leafgreen and Pokemon xd gale of darkness.
Lombre, Jigglypuff, Clefairy, Staryu, Shellder, Growlithe, Vulpix, Pikachu, Evee, Nidorino, Nidorina, Skitty.
EVEE
it doesn't evolve in Pokemon ruby.
Weezing does not evolve in Pokemon Ruby.
No because leafgreen has no in game clock feature so to get umbreon you need to train an evee in a game that has an in game clock such as ruby or diamond then once evee has max friendship it will evolve to umbreon during the night time.
Have firered or leafgreen trade one to ruby or get the one from Pokemon xd gale of darkness.
No because the game lacks the built in game clock feature which lets the game change from day and nighttime which is essential for evee to evolve to Espeon or Umbreon. If you want these pokemon you will need to use Ruby, Sapphire or Emerald to evolve the Evee because these games have the in game clock feature or you can even trade the Espeon and Umbreon from pokemon colosseum.