The Fire Tank
This is perhaps the best one-on-one class in the entire game. The purpose of this class is to out-last the opponent; this class can take a lot of punishment and is hard to control, allowing you to defeat your enemies without taking much damage.
The optimal combination is Immolation Powers with a Staff, Brawler, Two-Handers, or Martial Arts as the weapon choice. The weapon you choose should depend on your desired type of play.
If you are creating a true one-on-one dueling character who wants to be able to jump anyone and win in a 1v1, you will want to pick the staff. The staff is a stunning weapon, so it allows you to control your opponent as you steadily attack them.
Two-Handers are also a good choice as they speed up the rate at which you deal damage. The biggest weakness of two-handers is the slowness and clumsiness of the weapon; it makes them hard to use as you end up getting stunned a lot. The Fire class is immune to a lot of stuns, making up for this weakness.
Martial Arts and Brawler are for players who want to be good at PvP, but still want to play the player versus computer parts of the game. Martial Arts and Brawlers can allow your fire hero to be both a 1v1 powerhouse and a tank in player vs. computer action.
While the Fire Tank is the 1v1 master, it suffers in large-scale combat. Since it has to be in the middle of the fray to deal damage, it can be attacked by multiple ranged enemies. If you want to be good at both small and group PvP, I recommend the hero below:
Rifle and Gadgets
Another great PvP hero is the Rifle and Gadgets hero. By default, ranged weapons excel in PvP because it gives you a distinct advantage over players using melee weapons (especially if you get the jump).
Players who use Gadgets are weak against Fire and Ice characters. However, Fire and Ice characters tend to use melee weapons which are weak against Rifles. The Rifle covers your weaknesses so you can frequently defeat Ice and Fire players, even if they are using gadgets!
Weaknesses and affinities aside, rifles are perhaps the best PvP weapon since they are great at stunning your opponents. Every other class has to stun their opponent from melee range or use a casted spell (which can be interrupted) to stun, while the Rifle has an instant, ranged stun.
The instant, ranged stun combined with all the controls of the gadgetry class makes this synergistic combination perhaps the best PvP Class in DC Universe Online. The Rifle excels in both group and 1v1 PvP as do both branches of the gadgetry tree.