I know the game was not intended as a pvp game at all, but imo it's easy to turn it into an esport. I guess you won't see any solo duels because there would be too many imbalances (like I would just keep on using hdin and you won't see anything else being used). I'm talking about team duels because it is fully customisable and there's literally billions/trillions of permutations available for teams, so teams choose their own offense/defense. Not much room for complaints really. No single aspect of the team will make or break your strat so it's only about maximizing your effectiveness while weeding out weak points. Team pvp won't need guidelines on gear or sorb or whatever because no single item can counter the entire team, unless your team really sucks. The onus is on you to build a well-rounded team. Not sure what the current meta is though. If it's all hdins on each team then prolly better off as a non-esport :D . GM rules was probably the only real barrier to getting started in pvp. Nobody wants to read that list and adjust and restrict their gear/skills accordingly, so anybody that tried pvp either got booted out of gm games or got inducted into a bm game with no lower limit. Imo the biggest draw of the game should be pvp, so it is supposed to be easy to jump in and play. So basically no gear restrictions, and no skill restrictions (maybe ban bone wall because it doesn't really contribute to the dueling in any way and is lame in pvp. Maybe also leap/cloak of shadows/thorns/iron maiden. If there is a formal pvp feature those skills can just be greyed out in any pvp-only games). Imo there's only a few things to be decided on like those:
Pots allowed? - probably inconsequential whether allowed or not because it is applied to all chars across the board. Even if rejuvs were allowed it would still make for good games, as long as you can buy them for free from npcs. No need to worry about eshield sorcs being op because they were never that op to begin with. I reckon the current mana pots only should be the best setting, though
Charges? - sure. Banned skills should be greyed out in formal pvp games, though
Prebuffs? - imo don't allow. A formal pvp feature can enforce this by making sure you can't cast anything in town, and the moment you step on the blood moor you can't open your stash anymore for the rest of the match/round. Cube bo only
Mercenary? - doesn't make much of a difference but sure. Including this would probably only change the team strategy slightly to get rid of the merc and get it out of the way quickly at the start, though
The current gm rules exclude those in part because it's too much hassle and hence banned across the board. But if there were to be a formal pvp feature, those can either be made available at no charge or excluded altogether from formal pvp games. Esport or not, I think there should AT LEAST be a formal pvp feature. Prolly something that allows people to search for formal challenges from the bnet lobby, like what Warcraft 3 uses, or maybe something less anonymous.
I'd suggest a formal pvp feature where when you are matched up you are sent to a pvp only game, prolly with all monsters already cleared and no shrines or some area specialised for dueling, can buy pvp allowed pots for free and cannot use non-allowed pots, maybe free repairs, banned skills greyed out and unusable while in those games, maybe make it so that your char joins and leaves the game in the same exact state (same pots, same items w/ same durability/charges, same gold, same exp). But of course this is for GM or formal pvp only. If you want a ffa/bm game just create your own pub pvp game, where all the pubs will be.
And then if you really wanna make it popular (got like sick of playing in a dead game for the past few years. With a shit pvp scene you get like a shit trading scene), make an ingame auto wager system, probably with high runes or some other form of ingame currency (imo Blizz should set up its own ingame currency. At least then it will be convenient for ppl to trade), and THEN it would get really popular. The whole pvp thing would become a BUSINESS (it basically already was. Only it was controlled by a third-party in the OG). Anyway, some MMOs also make exp part of the wager. Maybe make a pvp ladder so there's your pvp stats on it or something, although pvp stats are not really a good indicator of anything outside of non-ladder because it's all gear dependent. There's a ton of ways to turn it into a pvp game. Maybe it will get more popular than pvm I don't know.
Other question is whether to use only the chars that you leveled and items you found and traded for, or just let people pick and choose all their chars and gears for free like on Asgard.
Also zons may be next to unusable in team pvp because of holy freeze, decrep, bone prison etc. Just boost zons IMO. A zon boost is like already way overdue:
https://forums.d2jsp.org/topic.php?t=84825989&f=384&o=0