All of these BCNMs require a Cloudy Orb, obtained by trading 20 Beastseals to Shami in Port Jeuno.

BCNM 20 - Shooting Fish
Allakhazam Link
Location: Horlais Peak
Participant Info: Optimal arrangement requires only two 20 SMNs with Ramuh. Third member slot can be vacant or filled with someone who's ready to just twiddle his thumbs.
Preparation required: Each SMN should have a Yagudo drink and 2 ethers for each run. All other items are optional. Fights should ideally occur on Lightningsday when possible, and never on Watersday.
Strategy: Simply put, this BCNM is cake with the SMN's Astral Flow. You can do it once per SMN participating. Enter the arena, apply Protect and Barwatera from your WHM subjob. Walk up the bridge but remain out of sight of the pugils. The SMN who is using his 2hr (determine this ahead of time, typically its the SMN who has used his orb for this fight) should then summon Ramuh, use Astral Flow and his Yagudo drink. Inch forward until you can Assault Ramuh on the Sniper Pugil in the center. Once he is engaged, trigger Judgement Bolt. Bam, massive damage to each of the three pugils.
Meanwhile, as the two-houring SMN is moving to engage, the second SMN should summon Ramuh as well, and Assault the Sniper Pugil after the first Ramuh has moved into range. After the first SMN uses Judgement Bolt, trigger Thunderspark. Sometimes, the Thunderspark will only hit one or two of the pugils, having a smaller AoE range than Judgement Bolt. If this is the case, Assault Ramuh on each of the three pugils in turn letting him get 2 or 3 hits on each, while your partner is waiting on his Blood Pact timer for Jugement Bolt. This step is typically unncessary, but it gives you something to do, and can save you in case of a resist or some bad luck.
For the two-houring SMN, stay close to your Ramuh, and have the other SMN stay nearby as well. Use an ether when your Blood Pact timer is nearing resetting, and be ready to trigger Judgement Bolt again as soon as its ready. If Ramuh dies, the pugils should go after the second Ramuh due to his Thunderspark. A second Judgement Bolt should kill both Archer Pugils, and leave the Sniper Pugil with a sliver of life left. Piece of cake to have the Ramuhs finish him off. You can then repeat this BCNM with the second SMN's orb and two hour.
Optionall, you can simply have both SMNs use their 2hr and do dual Judgement Bolts. This is safer than the above method (in which Ramuh can sometimes die at a bad moment and cause the SMNs to take aggro), but limits you to one run every 2 hours. However, this method is nearly 100% foolproof to win if you aren't fighting on Watersday.
Videos: Shooting Fish, no sound and a partial resist on the first two hour use. 17 megabytes, requires Divx codec., Shooting Fish, with sound and a RDM along for the ride. 75 megabytes, requires Divx codec.
DivX Codec Website

BCNM 20 - Charming Trio
Location: Balgas Dais
Participant Info: Ideal setup is 2 SMN and a WAR or PLD.
Preparation Required: Fight on any day but Watersday; ideally the day strongest for your preferred Avatar, typically Iceday for Shiva or Lightsday for Carby. Have the SMNs bring Yagudo drinks and ethers, the tank should bring half a dozen hi-potions, as the leeches will quickly drain away any buffs, food, or mp that the tank has.
Strategy: Coming soon!

BCNM 20 - Crustacean Conundrum
Location: Waughroom Shrine
Coming soon!