Eek, uhm, well probably the whole Indigo League - End of Orange islands. Not one series, but it's sort of an era before Johto came around.
150 Pokémon was always gonna be easier and some of those storylines kept me hooked!
(Bear in mind I was in primary school at the time, so I was somewhere between 4 & 12 ^^)
And not to mention Proffesor Ivy