The first 7 from
http://shoddybattle.com/stats are definitely the most accurate:
Gengar - It's difficult to narrow the most common gengar lead down. Most people tend to run different versions anyhow, which is what makes it so dangerous.
Bronzong - Standard, some running HP electric and going special to hit Taunt Gyara with a strong hit.
Gyarados - Usually Bulky, Taunt/DD and 2 attacks. Occasional hard hitter or scarfer for surprise factor, but prediction is fairly standard either way. I see people bashing it as a lead, but what's to hate about Intimidating every Physical lead, Taunting all the most common Stealth Rock leads (or Taunting their switch in, which makes prediction tons easier), and just having counters for the leads that send you running?
Tyranitar - Usually CB. Whereas you can counter other leads if you start out behind, TTar leads are common enough to where leading with something that can't OHKO and dies to pursuit (and doesn't have baton pass) is suicide. At least if you see it leading, you can make some pretty good guesses toward the rest of the opponent's team.
Salamence - Most of these tend to be Life Orbers right now. Specs are still somewhat popular and need to be accounted for, however. Always dangerous, but still seems to underperform considering.
Yanmega - This is -the- lead. Protect/Hypnosis with 2 attacks and focus sash beats just about every lead out there. Hypnosis and 3 attacks screws you when you expect to be able to wall it with something other than Blissey. Definitely a huge problem unless your team has this thing heavily covered.
Hippowdon - Mainly for Sandstorm purposes, of course. The real threat this thing poses is that you're going to have to deal with a heavy stall team behind it half the time.