6th Gen Kalos Gym Leaders Can Be Hard, Actually

Am I alone? I know XY are commonly regarded as among the easiest games in the series, outside of some obviously crosses like Sword and Shield, but there are some notable battles in the game that are pretty challenging, at least in my experience.

Viola - Not one of the notable ones, can easily be taken down by any Fire or Flying type. Surskit with Bubble may be a bit concerning but its really not a problem.

Grant - Dear Lord... Amaura will go straight for the Thunder Wave, and its Aurora Beam is surprisingly a strong move. Tyrunt is a complete bull in a china shop, with Strong Jaw powering up Bite, a powerful STAB in Rock Tomb, and a base 89 attack at this point in the game. This battle can be cheesed by doing the Steelix trade, but I'm trying to go all authentic here.

Korrina - Mienfoo is nothing, and Machoke is a strong offensive Pokemon hindered by its bad speed. But when Hawlucha comes out, the tables can easily turn. It has an extremely powerful STAB Flying Press, and Hone Claws makes this move even more deadly (and probably never miss).

Ramos - The most free battle in the game, just maybe watch out for Bulldoze Gogoat.

Clemont - Emolga has a relatively strong Volt Switch, but it should be nothing to write home about. Magneton can set up Electric Terrain, and has a heavy base Sepcial Attack. Heliolisk has good Special Attack, is specially bulky, fast, and has Grass Knot to ruin your Ground types. I recommend bringing Gabite, just switch out for Magneton as it will only survive two Mirror Shots and will die to a crit.

Valerie - Difficulty varies. If you've already done this battle once then its nothing to write home about, but if you're doing it all blind, (especially if it means being new to the Fairy type) oho, she's gonna beat your ass. Mr. Mime will break your Pokemon with bad special bulk most likely with one or two Psychics, and Sylveon has a strong Dazzling Gleam, but also high Special Defense + Cute Charm ability, meaning your forced to make contact with it while running the risk of getting infatuated. First timers will probably have the mistake of bringing a Fighting or Dark type.

Olympia - Doesn't get enough credit. Sigilyph can set up screens and Slowking won't deal much damage but just never dies. While you should already know Meowstics weaknesses, its still a decently strong special attacker with high speed. Also, all three of them have full movesets. Finally.

Wulfric - Easily crippled by strong weaknesses like Delphox, Aegislash, Chadizard, Lucario, Houndoom, Hawlucha, Tyrantrum etc.

Do I suck at Pokemon, or am I actually correct in what I'm saying?

I've thought for years that a lot of it comes down to team composition. Pokemon's generally easy in that if you are leveled adequately and have the advantageous type match-up, you basically win.

But sometimes your chosen team just happens to not be well suited to dealing with a particular opponent, and then you struggle a bit. I've had that happen before.

Agrees on the gym leaders being difficult with the wrong team. Remembers doing very little with Froakie versus Viola. Cannot take Tyrunt lightly, as you said. Has definitely gotten whacked by Heliolisk's Grass Knot. Understands Hawlucha demolishing someone.

Views them as comparatively weaker than past gym leaders, however. Cites two reasons (beyond overleveling):
1. Fewer power spikes. Points to BDSP gym leaders as example. Found Tyrunt scary at level 25. What about Cranidos's base 125 Attack at level 14? Flinches opponents easier than Tyrunt too, between Speed and part in the game.

Another BDSP example: Gardenia's Roserade at level 22. Cannot easily handle base 125 Special Attack and base 90 Speed then. Hits hard, even when resisted.

Faced several aces right at their evolution level (or before) in Black/White. Flexes at the peak of their power, potentially before your Pokemon's evolutions. See: Lenora's level 20 Watchog, Elesa's 27 Zebstrika, Clay's 31 Excadrill, Skyla's 35 Swanna, and Drayden's/Iris's 43 Haxorus (five levels early).

Sees much less of this in X/Y. Could have thrown Golem, Gigalith, or Probopass at you during Grant's gym. Did not evolve Korrina's Machoke, Ramo's Weepinbell, or Clemont's Magneton. Opted not to give Mega Evolution to any leaders either. Imagine Valerie with Mega Mawile.

2. Incomplete movesets. Sacrificed coverage options to make them more formidable. Embarrassed Korrina once because of it. Carries only one move that hits Ghost between all three Pokemon: Machoke's Rock Tomb. Sandbagged Viola's Vivillon by not giving it Struggle Bug, also.

Unfortunately I don't have much memory of how difficult the gym leaders in Kalos were for me, but I'm going to agree with Grant - that's one of the fights I remember actually losing the first time (iirc, at least). Don't exactly recall why, but I do remember Thunder Wave being a pain + Tyrunt overpowering the Pokémon I had at the time. I'm actually thinking of replaying this generation again, so this time around it'll be a better indication of how tough they are!

I had actually lost pokémon from several nuzlockes to Viola (hard mode hack), Grant, Clemont, Valerie and Wulfric. with Wulfric, it was mostly due to losing my charizard in the cave right before. with others it's lack of viable team members and variety.