By far the hardest at that point in the game, level 43 Alakazam are you *%&^ serious!(Psychic Pokemon were OP)...At that point my highest level pokemon was 38. I had to skip her until after I beat Blaine.
2nd Gen: Clair (Silver & Gold)
I would have said Jasmine, but DragonBreath+smokescreen+Kingdra=annoying as hell, not to mention that all her pokemon kept on paralyzing me with thunderwave.
3rd Gen: Tate & Liza (Emerald)
I didn't take Tag battles seriously until this point, and its the first time i realized how tough it can be to take down two pokemon (Solrock & Lunatone) that work so well together.
4th Gen: Fantina (Rematch)
4th Gen was easy as hell no gym gave me trouble in Diamond and Pearl, but if i had to say one i'd guess I'd say Fatina gave me some trouble when i rematched her.
5th Gen: I didn't play black or white
Thought you could take my name, my game, my story, my glory, my fame! --(Psn: LunaticHighZZZZZ)---
1: Yeah, probably Sabrina. There was no good way to take down Psychics aside from brute force which was hard to do because her levels were pretty high.
2: Whitney when I was a kid. Most other gyms weren't too bad, though on the odd occasion I didn't pick or use Cyndaquil, Bugsy's Scyther could be tough, namely in the remakes.
3: Liz and Tate. I've never finished Gen III, but those two ended one of my Nuzlocke's. Wiped out my ENTIRE team.
4: No one really. I guess Roark can be tough because Cranidos packs a hell of a punch, especially that early in the game.
5: Lenora if you didn't pick up one of the Fighting types, which I never did (aside from Pignite) because they are all ugly. Watchog is annoying with Hypnosis and that first Retaliate pretty much rips apart anything not named Roggenrola.
1. I dunno. Probably Sabrina, since she's psychic type (If I remember right) 2.Whitney. Do I even need to explain? 3. Was not familiar with Gen 3 gym leaders. 4. Probably the ice type leader, whatever her name was... 5.Clay. Dat excadrill.
Mentions of Zangoose since 6/27/2013: 1 Official Shadow Zangoose of the X board!