Why are some pure Fighting-type Pokemon weak to Ground-type moves while others aren't?

Question

Notice how some Pokemon who are purely Fighting-type weak to Ground-type moves while others aren't. For example, if a Pokemon used Earthquake on Hitmonlee, who is a pure Fighting-type Pokemon, it's super-effective. However, if it's used on Machamp, who is also a pure Fighting-type Pokemon, it is neutral. May someone explain?

Comments

Hitmonlee will not be hit super effectively by a ground type move. You must be mistaken.

---

McRibFarewellTour, I don't agree. When I challenged Bruno in Pokemon Heart Gold, I used Earthquake on his Hitmonlee and it was super-effective. However, when I used it on his Machamp, it was neutral.

---

Record the footage and show us.

---

Are you sure you didn't mix up Hitmonlee for Onix?

---

VoltMadness, I'm sure. I will try to send footage ASAP.

---

It may be a glitch. Are you playing on a emulator?

---

Yes. I was playing on an emulator.

---

There are two explanations:

1.) You're mistaken/misremember it.
2.) It's a glitch.

Hitmonlee is neutral to ground. This isn't an opinion, it's literally an objective fact in the form of the games code which can be observed and replicated.

---

Are you able to get a video?

---

what game were you playing on this emulator

---

I was playing Pokemon HeartGold and I didn't make a video yet.

---

You’ll have to provide a video before the 7 day mark of this post, or else we’ll close it under rule 1.4.

---

I stand corrected. I am wrong about how some pure Fighting-type Pokemon are weak to Ground-type moves while others aren't. I have uploaded video evidence of me being wrong. https://www.dropbox.com/home?preview=Video.mp4

---

It says that the file doesn't exist.
That's not how that works, you need to create a shareable link for the file, if you click on the video you uploaded and then copy the link on the address bar, it doesn't work. Please do that before the 7-day mark.

---

We don't need a video that confirms what we already knew. We can just take this off the unanswered list now.

Answer 1

It appears that I am wrong. Ground-type attacks aren't super effective on pure Fighting-type Pokemon. Below is a shareable link to the file. Please click on it.

https://www.dropbox.com/s/huds1x2yb6vlxti/Video.mp4?dl=0

Comments

Glad the question is resolved but this video hurt my soul xD

Also (spoiler) why didn't Hitmonlee lose 50% health when it missed HJK? Is the damage different in those games?
Okay so Bulbapedia says in Gen 4, HJK crash damage is 50% of target HP, so now it makes sense.