No you can't. Gible is in the sinnoh pokedex, so you can't get it in emerald. sorry
yes, in wayward cave,
you cant he is only in pearl, diamond
Gible is not found at a route. Gible is found in Wayward Cave. Wayward Cave is under Bicycle Road. Gible is hard to find though.
Gible doesn't exist in sapphire.
There is a cave beneath the cycling road. There will be a Gible in there.