no
look in the Pokemon tower in lavender for haunter. note, haunter is hard to find in the Pokemon tower
no unless you know how to hack
I don't know but i think you can.
no
venusaur,moltres,magneton,mewtwo,haunter,vaporeon
BUY IT
No.
Get 50 Pokemon...
It is not possible to get all three starters in Pokemon LeafGreen without trading. This was an intended mechanic to encourage interaction between players.
Haunter only evolves into Gengar through trade. If you're using a generation 4 Pokemon game you can deposit Haunter into the GTS and trade for any other Pokemon in the GTS, then take back your Haunter and it will evolve.
you have to trade from emerald