I cant play the game without going 0-22 or 1-19 if i get lucky with a nade kill
i though i was just outmatched but i came to know that those people used some controller exploits which allows them to use 8 burst br double beat-down flying far with sword
paired with aim assist halo 2 is unplayable for someone new like me
halo multiplayer on pc has been a big flop
only original xbox ogs play the game , finding a new player is like finding nemo.
The use of grenades (curve, type, timing, suitable places for bouncing...) and the right understanding of melee mechanics (not necessarily including button combinations, as it's essentially different from the other Halos by default in the sense it's not the same punching staticly than moving or jumping) are key to how a match works in Halo 2 Classic, just like map knowledge and decision making when using one weapon or another (the BR is certainly strong in most situations and will help you outgun less skilled players, but time will tell power weapon control is really vital, and dual-wielding can mean a victory at the right moment and distance). Luckiness can save you once, but won't do so consistently.
As far as I know, the trick you're referring to is exclusive to the campaign and doesn't work in the Multiplayer section of Halo 2 Classic for balancing reasons. It's called "sword flying" and was only re-added to the game for certain speed runs as the the original fans wanted them for the sake of fun. I can understand why this specific multiplayer can be frustrating for new players, but I started just like you in MCC and eventually learnt to both, enjoy and be a valuable teammate. Now, Halo 2 Classic is with no doubt my favourite iteration of multiplayer for countless reasons (vehicle health system, skillful and deep melee system with a decent range, power weapons that guarantee movement around the map, encouraged and powerful dual-wielding when used tactically, well-thought map layout, quick action, interactive elements...).
Aim assist is a concern just like the mouse freedom at any range, speed and precise target adquisition. To be honest, once I switched to mouse and keyboard, I haven't thought of coming back to a controller. While it needs training to have potential in the multiplayer environment, the moment you reach the proper skill ceiling it can be really competitive. Whether one input device or the other is better is up to debate, thus the developers have finally opted to split them up on demand and leave anything as it was originally.
From my point of view, as a new player you just need to either stay away of this side of multiplayer or learn progressively (I'd recommend starting with BTB, SMG starts or Objective modes, then try BR Slayer 4v4 and when you feel you're getting better you could return to Objective for a more tactical approach). I won't deny button combinations can be seen as an exploit, but the frequence you'll see them employed in Social Games is next to zero. In addition, believe it or not, mastering the only useful ones (BXR and RRX - Double Shot) is not an easy task by any means, and they are not necessary at all to be near (or even at) the top of the scoreboard. The points I mentioned in the first two paragraphs are some of the actual improvements a players needs in order to perform properly in a match. Not only that, knowing how to counter button combos is also a possible move, and they're not going to be patched at this point. Your current results are not due to them being in-game. Removing Halo 2 Classic in favour of the fusion that is Halo 2: Anniversary would be the most non-sensical decision I have ever seen, there's no way anyone could agree with that point. You can see my thoughts on that remake here: "How to make H2A an actual successor"