http://www.psypokes.net has it all
u can trade a golduck on route 18 for it
Go to Route 18 and trade Golduck for a Lickitung. Pokemon Leafgreen Version requires a Slowbro instead.
The earliest route you can get it at is Route 4.
Route 225 is not a route that can be found in Pokemon Firered, route 225 is in Pokemon Diamond, Pearl, and Platinum. To get there is Diamond Pearl and Platinum, you have to see every Pokemon in Sinnoh, then talk to Prof. Rowan and get the national dex.
route 23
route 3or4
Route 6.
You can trade an Abra for Mr. Mime in a house on Route 3 in Pokemon FireRed.
pidgy and rattata
look on your map
You can get a lickitung in fire red by trading with a kid in the building that is in between fuchisa and route 18. You trade him a golduck.
Route 11 is just east of Vermilion City.