Because he doesn't.
in Pokemon leaf green red blu and gold
Ada
one in a bout 8200 Pokemon will be shiny. A shiny Pokemon is a Pokemon that appears to be a different colour, when this happens they will be a bit more stronger. for example a golbat is blue with purple wings a shiny golbat is green with pink wings
green golbat is a shiny golbat so if you search for you have 1/8392 change that you find 1
you need to have max frendship with golbat, but i think you need to trade to ruby/sapphire/emerald, then have it love you, then trade it back
It evolves at lvl 22 into golbat then Crobat by getting max happens
in leaf green you cant find ekans, arbok, oddish, gloom, vileplume, psyduck, golduck, growlithe, arcanine, shellder, cloyster, scyther, and electobuzz but you can trade them from fire red.
the wild Pokemon which you can find in victory road on leaf green are: geodude, graveler, zubat, golbat, onix, machop, machoke, sandshrew and if your lucky enough to find one then sandslash
Get Golbat to love you (catching it with a luxury ball will help) then level it up once
they actually carry a variety of Pokemon like arbok ekans koffing weezing grimer and muk and rattata and raticate im not sure if that's all but the boss carries big strong Pokemon and ground Pokemon.
Sadly, Crobat can't Evolve because it's the last form of Zubat. Zubat --> Golbat --> Crobat. ^^ Good Luck!
what r u talking about? golbat is blue in the first place,unless you have a shiny. If you have a shiny, then i dont think it will turn back to blue when it evolves to crobat. my brother has a green zubat, but it didn't evolve yet.