So I have been hearing a lot of these terms. One day my friends were discussing about which is the best HM slave in Pokemon Diamond version. I didn't know what a HM slave meant, so I went to ask someone. But the person I asked said that it should be called an HM mule. So what is the difference? And if there is no difference, is there a more commonly used name out there?
Thanks!
No, there isn't
These two terms' meaning is the same.
HM Mule:
HM mule. A term used within parts of the fandom to refer to a Pokémon in a Trainer's party that is used for navigational support through the use of field moves—generally those taught by Hidden Machines.
HM Slave:
An HM slave, then, is a term for a Pokemon that is not used for battle but knows one or more of these moves (referring to the HM Moves), such that the battle performance of your other 5 Pokemon is not diminished by "wasting" one of your 4 attack moves with an HM move (which are generally subpar compared to other, similar, options).
It’s just that, and Slave is also an offensive word, as mentioned before.
Source 1 Source 2
Hope I helped!