Imho, you could do the following things to make it viable and fair (easier) for newer players (off the top of my head).
- Disable MVP and Mini Boss cards. Yep, Clowns become extremely important immediately. Ganging becomes important. Gravity themselves have acknowledged that MVP cards were never meant to be used on a large scale, so they technically break the game. If you want to make it a fair battle arena, where well geared, and not so well geared people can compete on a more even scale. At the same time, keep all the customs active, so that people can still create an impact with gear that they worked hard for / donated for with hard-earned money.
- Bring back status afflictions (can't think of the right word =p). I don't just mean stone curse and freeze, but the lesser known/seen (in pservers atleast) ones such as sleep, stun, confusion etc etc. For example, 97 vit used to give stun immunity, we could have something like 300 total vit gives immunity (ye, not THAT easy to get.). They were put into the game for a reason, and personally, I've always felt that they require players to have a higher skill level in order to make more of an impact.
- Usual WOE reducts and whatnot.
This, along with all the suggestions given beforehand, could help. BG is one of the best examples of the fast paced team PVP that RO brings into the fold, after woe and GVG. The problem with the latter two are that it usually requires a large amount of preparation/supplies/planning. I've only being playing for a couple of weeks, so please excuse any lacunae in my knowledge about this server. Cheers. xD