So, there have probably been threads about your favourite gym leader. But I wanna know is: Who is the smartest gym leader? 

A gym leader can be smart in anyway: The Pokémon order, status ailments, brute or smart attacks, anything.

I haven't fought all gym leaders in the Pokémon Universe, but one of the smartest is Bugsy. First he sends out Metapod and Kakuna who will mostly use harden just to tire your Pokémon out, and if you're unlucky one of Kakuna's rare poison stings poisons you. But then Scyther comes. At first you think: Fury Cutter is weak. But then it gets strong and when he defeated your first Pokémon the rest is just to follow, because fury cutters base power is 120! at it's highest. Very annoying.

So tell me who is the smartest gym leader according to you!

That is freaking hard!! There are a lot: Giovanni,Brock (If you play ash gray or Pokemon yellow) And so much more. I'll edit this post when i think of more

Maybe Whitney?

imamonster : Ugh Whitney was hard too. Clefairy was not that hard of a deal but it was a solid Pokémon with Metronome (can be in your luck, or completely against your luck), mimic to steal one of your good moves, Encore to keep you using the same move over and over, Double Slap just to damage you  but Miltank... Rollout gets stronger just like fury cutter, Milk Drink to regain HP, Stomp is just good for raw damage and attract to keep your males in love... She's very smart too

I agree, Bugsy is pretty smart but who is smarter: Blaine!! 
Why? Because his combo of brute force and good strategies actually, truly works!!
And the only reason Ash beat him was because his OPed Charizard was actually obeying, just to fight magmar!!

Seems like I'm not the only one who thinks Whitney was a pain in the you-know-where. She is one of the most challenging gym leaders in silver and gold if you haven't trained your Pokémon's enough.

Also Clair gave me some hard time with her insane Kingdra.

frizyboy11 : The last gym leader I fought in Red was Koga, after that I stopped... But still, Blaine is pretty strong with his brute force and his burns can make him pretty irritating too. Blaine is smart in the way of dealing damage I would say.

Cactuar : Yes, almost everybody thinks that Whitney is the most annoying gym leader in Gen II. But others are pretty good too: Falkner his Pidgeotto is very tough to defeat, Morty's Gengar is incredibly strong and so on. I didn't have a hard time with Clair but that was because my insanely strong Feraligatr, the only Pokémon I trained, was strong enough to deal with her whole team. I sent out my freshly caught Piloswine though but one of her Dragonairs quickly killed it with Surf >O<

greenluigi : Yeah, I had a load of trouble with Brawly as well until I used a Sableye as fighting types can't hurt those. 

In my opinion, Whitney (Gen 2) and Elite 4 from D/P/P are the hardest things to beat in the game, but far as smarts go i give the award to Blue (Took after as Gym Leader in Viridian City for G/S and HG/SS). The reason i say this is because unlike any other gym leader Blue has multiple types of pokemon, making it a more well rounded team, when you can go get yourself a water type to wipe out Flannary from Gen 3 and a Steel type to easily get Roxie in Gen 5. (Its possible via Magnemite). Along with this they are found in the 1st two Gen. of pokemon, which i find a tab bit harder than the proceeded games.

LANCE OF POKEMON STADIUM 2!! I got an idea HYPER BEAM. the only gym leader i could never beat. :'(

Pokefreak219 : I haven't done the Elite 4 in Platinum yet but they are my next opinions, they sounds tough as hell I agree, the gen 1 and 2 Pokémon miss many fancy moves and it's always useful to have a balanced team.

clifton123 : I haven't played Pokémon Stadium 2 but Lance sure is tough and very smart. He even uses dragons who aren't dragons :O

sabrina is the phychic types and she's intellegence

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marianne26 : Haha, that is the most logical answer indeed, she is said to be smartest. Also, what a cool picture! My constellation is the Scorpio so I would be a Skorupi.

Whitney from Pokemon Gold, Silver and Crystal. I mean
what the freak!!! If you had played those games you know
that on mistake against this tough chick equals death
to your whole pokemon team.

Banenzo : I couldn't beat Whitney until my Croconaw was level 30 and it was the only Pokémon I used against her, that just shows how tough she is.

juuldude : I agree with you and Banenzo. Whitney was the first real gym leader that took me a couple times before I actually beat her. I usually had no problem with her Clefairy, but that stupid cow (Miltank) just kept on using Rollout against my Quilava, so it didn't have a chance. I had to use other (less stronger) Pokémon in my party before I actually beat her. And on top of that, the first move she would always use was Attract. So sometimes, my Pokémon couldn't even use an attack. At the time, I thought it was almost impossible to beat her. I had to level up 3 of my Pokémon to at least 25 when her Miltank was only a 20.

But she wasn't the only one I had trouble with the first time around. I also had a lot of trouble with Morty. I remember his Gengar just kept using Hypnosis that put my Pokémon to sleep. Then he used Dream Eater and beat me without even trying. He was using a smart but simple strategy too. Back then, I was young and naïve though. So once I figured out that I could buy an Abra at the Game Corner in Goldenrod City, and raised it to a Kadabra, Morty was no match for that. But I had to buy and use a bunch of Awakenings to get by him though.

MattyIce : I always have a lot of male Pokémon so I agree, that's pretty difficult.

Morty is a tough cookie as well yeah, putting you in sleep and draining you. Like you said, simple but effective. His Ghastly is a joke though, just like his Haunters.

That would be Sabrina for using psychic Pokemon in gen 1, and Candice who decides to use a hyper evasion stall that makes smogon cry.

Cradily is love : Yup Sabrina is tough with her Alakazam especially And what is Smogon?

juuldude : Sabrina is no problem in subsequent generations, her alakazam is still a good Pokemon, and smogon is a competitive league.