I know that the Halo 3 Medals won’t register for in-game stats, but I’ve been getting beat down medals across all titles, not just 3. For whatever reason though, they don’t seem to update properly. Oh well lol
Since the achievement only asks you to get beatdowns in multiplayer games, you can technically get them in Customs and Spartan Ops. Keep in mind that the modern definition of "Beat-Down" is different from the classic definition. A typical melee kill nets you a Melee medal, while a melee from behind (without triggering an assassination in H4) is a Beat-Down.
The buggy nature of those medals are what I was referring. KOTH medals don't count either even though Halo 3 has a number of those.
Any chance you’re playing H3? For whatever reason, a lot of medals don’t count for achievements when you play H3.A lot of that is due to the fact that certain medals don’t even appear in H3 such as Assists, even though the game still counts your assists in that game. Beat downs though, I’m pretty sure H3 has them and them not tracking could simply be due to the glitchiness of the game. Had this happen many times when going for legendary medals.
I believe that Halo 3 has only one KotH medal: Earning 5 kills while in an uncontested hill. It's a really poor choice for earning KotH medals. The better games are 2, 2A, and 4.