The most well known set is still the best. Will-O-Wisp is the backbone of the set allowing Weezing to seriously damage the offensive output of physical attackers. It also slows down Weezing's counters like Latios and Rotom Wash. Flamethrower is the next move as it lets Weezing incinerate Ferrothorn, Scizor, and Skarmory while doing something useful to Espeon. It also lets you handle some Venusaur. Pain Split isn't perfect for healing but it can keep Weezing around a few turns longer than it would otherwise. It's also one of your best weapons against Heatran as it can take a decent amount of HP off the magma Pokemon
Options: The last slot is dependent on what your team needs. Thunderbolt is almost exclusively for Gyarados and Cloyster. While it does hit Politoed, Tentacruel, Jellicent, and Starmie hard it doesn't really do enough damage to beat any of them. Hidden Power Ice is a good move to take on Gliscor and Landorus with as you are either immune or otherwise tough enough to take anything they have. Hidden Power Ice also takes a solid chunk off the common dragons of OU, though you will not usually take those dragons out without being crippled yourself. The last attack option is Hidden Power Ground. It is your best option to take out opposing Heatran. It also help against annoying Toxicroak and does a bit more to Terrakion.
Counters: With the defensive EVs Weezing can safely counter Gyarados, Lucario, Landorus, Breloom, Scizor, some Terrakion and many other Pokemon.
This is a good moveset for weezing (Pokemon #110) with the levitate ability/trait, a Bold nature, and equipped with Black Sludge submitted by Cybermewtwo. For use in competitive Pokemon battles featuring an Export option and breeding guide.