Pures are really best for pking, I've found. You'll need to think outside the square for staking. When I was playing a runescape classic private server, I found that many people went pure defence. I did stake a little with a pure and it worked for a while. If you wanna stake just other pures, get 40 attack and as high strength you can get. I found that lots of people had a bit of prayer, so when I turned it off, I had a bit of an advantage. Anyway, remember you'll get dominated by mages and def nubs.