It depends on what game version it is, Pinsir is available in every game version (except for Pokemon Blue, the version that is only in Japanese) but however, rare. Whilst Scyther cannot be caught in the versions Ruby, Sapphire and Emerald. And is both rare and common depending on the version.
It depends which version you are playing. Red/Blue version: You can find Koffing in the Pokemon Mansion, however he is rare in Blue version. Yellow Version: He cannot be found in Yellow. Gold/Crystal/Silver version: You can find him in Mahogany Town or the Burned Tower. Ruby/Sapphire/Emerald version: You can find him on the Fiery Path, however he is rare in Sapphire version. FireRed/LeafGreen version: You can find him in the Pokemon Mansion, however he is rare in LeafGreen. Colosseum: He cannot be found in Colosseum. XD: He cannot be found in XD.
The rare, non-legendary Pokemon in Generation I (Red, Blue, Yellow, Green) are:PikachuRaichuClefairyClefableVulpixNinetalesMeowthPersianFarfetch'dExeggcuteHitmonleeHitmonchanLickitungRhyhornRhydonChanseyTangelaKangaskhanStaryuMr. MimeScytherJynxElectabuzzMagmarPinsirTaurosLaprasDittoEeveeVaporeonJolteonFlareonPorygonOmanyteOmastarKabutoKabutopsAerodactylSnorlaxDratiniDragonairDragonite
Syther is not available in Blue version and must be transferred from Red version.
no
clone rare candies
no
not possible
by cheat
Some what rare I think. Because I have the full foil version.
The Viridian Woods (Rare)
No; in FR version, there is no level-up code. There is a code to get max Rare Candy codes, however.