In the pokemon tower in Lavandor Town, you must have the Sioph Scope which you get in Cledlen City after defeating Giovanni. The Marowak is the spirit of a mother in which members of team rocket killed. It is at level 30 and can not be caught. Sorry!
Scyther which can be caught in the bug catching contest also firered can get it and a shadow scyther is in Pokemon xd gale of darkness. Marowak which can be caught at seven island in firered and leafgreen also you can train a cubone to level 30 to get marowak.
you will get Gastly, hunter and the gost is a Marowak.
Piplup does not exist in Pokemon LeafGreen or FireRed.
No, you cannot find cyndaquil in LeafGreen.
you should go to gamestop
In Pokemon Yellow you have to find the silph scope, and then go the the tower and it is the unidentified ghost!
LeafGreen version does not have Growlithe.
In the grass...
You cannot catch houndour in Pokemon leafgreen either get one from Pokemon emerald or Pokemon colosseum.
the flute is given by Mr Fuji after you defeat Marowak in the Pokemon Tower or the graveyard.
there is no such Pokemon
That item doesn't exist in leafgreen.