You don't need a badge to get strength but you need a badge to use strength and that badge is the rainbowbadge and that is the 4th one in celadon city.
the one you get from the gym in fuschia city.
you find chinchou under the sea when you diveChinchou cannot be obtained in LeafGreen you will need to trade it from Emerald.
you need to find it in the safari zone in area1.
just trading ------ Oddish is a Fire Red exclusive Pokemon. You need to trade to get it.
You don't need a badge to get strength but you need a badge to use strength and that badge is the rainbowbadge and that is the 4th one in celadon city.
the one you get from the gym in fuschia city.
Articuno is in Seafoam Islands you need the HM Strength to get to it though and the HM Surf also you need the 4th and 5th badge.
Cinnabar Island, you need to surf South from Pallet Town.
You'll need to trade for it from Pokemon FireRed.
Teach it the HM move Strength. You will also need the badge from Celadon City which will allow you to use Strength outside of battle.
The reggis are not available in leafgreen you will need Ruby, Sapphire and Emerald to give you them.
we need to know which one.
you find chinchou under the sea when you diveChinchou cannot be obtained in LeafGreen you will need to trade it from Emerald.
Navel rock to get there you need a mystic ticket. Also you can trade the lugia from Pokemon xd gale of darkness to leafgreen.
you need to find it in the safari zone in area1.
You have to trade it from Firered/Leafgreen in Pokemon firered/leafgreen you can find zapdos in power plant, but you need surf to get there.