really simple on why Tornadus and Thundurus learn so many dark moves comparing to the other two, one of their ability is prankster, they are troublemakers

I think part of why Klinklang isn't Electric type is the idea that it's supposed to be a perpetual motion machine. The rotation of it's gears can be used to conduct electricity while the Pokemon itself is the one perpetuating the motion itself without an external energy source.

1:53 It's still weird to me that Leech Life is a good move now.  I grew up with it only being used by low level Zubats with a base power of like 20.

Empoleon has always learnt Steel Wing since its introduction in Gen 4, it’s just not a TM anymore but was until Gen 8 :)

The Pinsir one shocked me. How does he not get megahorn or leech life? Both make so much sense

I thought at first this video was about Pokémon learning literally wrong attacks like Great Tusk learning Psyshock.

This video just shows me that Gamefreak needs to make non bird based physical flying moves. Just make a 1 turn accurate version of bounce Called sky dive

What about moves that learn the wrong pokemon

4:41 It is because it was the villain in VGC before Twave and Swagger nerf.

It's really funny when you look back at the older Pokemon games, particularly gen 1/2. A lot of Pokemon in those early games are lacking STAB moves. One of the funniest is Gligar who gets zero damaging Flying/Ground moves in gen 2 by level-up or TM. The only flying move it can learn is Wing Attack by breeding. It also took until gen 8 for Gliscor to get a Ground attack via level-up.

10:38 It gets Steel Wing in gens 4, 5, 6, 7, and BDSP by TM. Steel Wing is a TM in SS, but it isn't in SS, and Steel Wing is no longer a TM in SV, so it doesn't get it.

Funny enough, I think Mawile was supposed it be Dark type, but was changed to steel because there was so few steel types in the game

I don't get why Empoleon is a special attacker. Its design just screams physical attacker, and it'd likely have Sharpness if it was added in Gen 9 or future gens. I'm partially convinced they only made it a special attacker because Torterra was already physical and Infernape is a mixed attacker, and they typically try to have at least one physical and one special attacker in each starter trio (after Gen 1 at least).

Somewhat related but also kind of baffling: there isn't a widespread Steel-type cutting/slicing move. The only two are Zacian's Behemoth Blade and Iron Crown's Tachyon Cutter.

Thundurus and Tornadus learn so many dark moves because they're partially based on demons
In Chinese Mythology, you can force a demon to reveal its true from with a special mirror, which is how the Forces of Nature access their Therian Formes
also, in lore, they're tricksters and love messing around, hence why their abilities are Prankster and why they listen to Landorus since he's the straight man of the group

When I was a kid I always thought Groudon is a fire type mon and kyogre water making a fire water rivalry.

Very unlikely that Gyarados would be dragon-type: there are lots of stories in east Asia where dragon loses its dragon status for bad behavior, and "bad behavior" for Gyarados' behavior is such understament that it’s close to lie.

6:40 actually in the teraleak it was shown that Flabebe and its evolutions were planned to be fairy and grass but since fairy was the new type, Gamefreak wanted a new, pure Fairy type, three stages evolutionary line Pokémon.

Mega Pinsir is one of the stronger Megas in singles, and typically doesn’t use a single STAB move (not counting Aerilate boosted Normal moves by technicality)

Not that he really needed any Bug STAB anyways since his job is to clean up the late game once all of the Flying resists are off the table.

I can get the argument of Flabebe and Floette not being Grass, but Florges has clearly merged with that flower- I don’t think it’s unreasonable to think THAT should be Fairy/Grass.

And on a similar note, yeah, Comfey being Fairy/Grass wouldn’t be too out there.

Here’s a breakdown of Mews move pull in Gen 9
Bug - 10
Dark - 9
Dragon - 7
Electric - 10
Fairy - 6
Fighting - 12
Fire - 14
Flying - 8
Ghost - 6
Grass - 14
Ground - 11
Ice - 9
Poison - 7
Psychic - 9
Rock -  8
Steel - 8
Water - 12
It has more Bug, Electric, Fighting, Fire, Grass, Ground, and Water moves than Psychic; as well as the same number of Dark and Ice moves. But no individual type is twice as much as Mews STAB type