Wallet Warriors are yet another unfortunate side-effect of the way the game is set up. Rather than play through the game normally, use what is given by the Random Number Generator, and pick up the occasional upgraded item with the gold the game gives them, they take it to the extreme opposite end of the spectrum from the Sandbaggers. They break out their credit card and sock their armory full of the latest LE weapon-du-jour. They power-level their heroes, using gold to skip the wait time and XP gains required. And they annoy the crap out of the free-to-play (or mostly-free-to-play) players when they turn up as an opponent in PvP.
So what can be done about them? Not a whole heck of a lot, unless Playdom wants to cut off a revenue stream. These PvP Whales are what really keeps he game going. They're the ones dropping hundreds of dollars on gold on a monthly basis. The best a F2P can do is try to save up their gold and buy judiciously when it comes to boosting their PvP bonus or trying to get new heroes. The F2P player can re-run lower-level areas to try and build up their stock of CP so they can buy new heroes, running them on 20-minute flight deck missions to get them up to snuff as quickly as possible. In the worst case, if you can't beat them, join them. Wait for Gold Sales and pick up $20 worth at that time. The 100+ gold that nets you can easily get you one or two heroes or alternate uniforms, which may give you a little bit of a leg up.