Since we saw most of the Heart Pirates abilities, I want to create a documented explain their ability and my assumption on how their ability work.
Law has the Ope Ope No Mi and is capable of ‘Awakening’ it. From what we see in Chapter 1064, Law only use his Awakening technique with ‘Re-Room’ and ‘K-room’.
To explain Re-room or what I call ‘Remote room’ made Law able to apply the Room effect to the target directly (remember Awakening for paramecia made you able to give your devil fruit property to an Object or Target) while K-room or what I call ‘ Katana room’ or ‘Kikoku room’, it is where Law apply Room to his Sword. The reason Blackbeard is So surprised by Law’s ability is that BB never knows that Law can use Room’s ability Remotely but Amputate is a normal Law cut that he uses since Sabaody with his normal Room.
Re-Room or Remote Room
K-room or Katana room where he made his katana (Kikoku) extend the length.
Shachi and Penguin
As far as we know Sachi and Penguin are not Fishmen or Half Fishmen. In Chapter 1064 Penguin said he and the others grew up in the frigid North Blue port, they have the advantage in a sea battle. The underwater fighting technique isn’t exclusive to Fishmen, plenty of characters used to fight underwater before. For example, Sanji can use the skywalk technique underwater to make him faster than swimming, Koala is a Fishman karate expert, etc. However, Shachi can also extend his body and suck up a large amount of water. This can simply be explained by the fact that One Piece characters can train and have great control of their body. The perfect example is Kumadori from CP9, he is the character I always used to explain weird techniques people in One Piece use. To his explanation, humans can control every part of their body.
Shachi extends his body so he can suck up more water
Frigid North Blue Port
Kumadori turn from fat to normal
His explanation of Humans being able to control every part of their body freely
The Heart Pirates
Similar to how we see the Straw Hat Pirates crew team up to fight Oars, we now see how the Heart Pirates fight as a Team (only five main guys, Penguin, Shachi, Bepo, Jean Bart and Hakugan for Polartank).
They are ‘Naval Battle Experts’. To add more to it, they are also defensive/counter-type fighters. All Law asks for his crew is to provide cover and counter attack them with an underwater attack. Shachi, Penguin, and Hakugan (sail Polar tank) provide a cover for attack from the ship/the sea. Bepo has the defensive ability to locate enemy Snipers with his ear (arguably that he also uses Observation Haki). The most defensive meatshield in Law’s crew is Jean Bart who can tank Van Augar’s attack (can be Iron body or Armament Haki). Law is a glass canon and the main damage for his entire crew and he perfectly uses his crew as a cover. We see a lot of times where Law is always able to use his strongest attack after somebody, best example is his fight against Big Mom: Kid tanks a lot of damage with his scrap so that Law can launch his attack at the perfect time. His crew provides that defensive gap Law is missing. So Law can focus on building up his strongest attack and launch at the perfect time. Lastly, the most destructive and highest raw damage still hidden in Law’s crew, Bepo Sulong will appear at some point in the story. and that would be really fun to see.