shark summons would be peak. kisame was cool asl w it too. like there was that water shark bullet technique that attacked gai and aoba.
and rationally, shark summons would be more useful largely for shinobi from kirigakure. so obvi we didnt see much of it. but still, i love sharks so i js always imagine its there.
the boss summon would be a great white shark, which would be huge like around the size of gamabunta or shukaku during the konoha crush. i think its pretty universal that great whites rep a kind of raw, crushing force, like tsunade's hits. especially since unlike the buccal pumping of nurse sharks, great white sharks have ram ventilation, which basically makes it so they have to keep moving to breathe. basically a de facto relentless, constant-motion attacker.
the specialists for like combat would be hammerheads, but anatomically, their heads give them 360-degree vision and a sort of electrical sensing. so they'd be useful with their sensory abilities during strikes and fights. literally immune to being snuck up on and would be able to track enemies through visual obstructions.
then obvi the mako shark (literally my fav since i rammed into a public library bookshelf reading its shark facts page) would be the speed specialist. especially the shortfin mako since its the fatest in the world. it can fr go up to 60 mph, probably even faster with chakra. their nickname is "murder torpedoes" so they'd be used for fights or a transport summons for urgent missions. like how naruto needed to get to suna fast after hearing abt gaara being taken by the akatsuki (yes ik there wasn't much water, but for example). i imagine there would be more shortfins than longfins, since longfins are more rare. but the longfin mako would be used for a few deep-water uses, since they don't prefer to go as fast, and they stay offshore.
the nurse shark would be perfect for like ambushes or stationary traps, because they're more slow-moving and they stay close to the ground. they can stay still and breathe via buccal pumping for underwater ambushes. actually, did you know that nurse sharks, especially, they have this like rlly strong suction power, so they expand their throats into an intense vaccum with up to, i think it was 245 kPa. maybe more.
and then bull sharks would be the more wide-spread, all-terrain support kinda summons. some species of shark are more picky about what kind of waters they got into, but bull sharks are more versatile and can survive in both saltwater and fresh. so shinobis don't have to worry about what kind of water it is as they're summoning, it can be anything from a river to the open ocean. they're incredibly strong, with their bite force, and i imagine they could actually pair well with a thresher shark. like the tresher wears down the opponents by using their longer tail as a whip kinda thing, and the bull sharks pair it with a final strong bite to finish them off in their weakened state.
thats also a drawback i imagine. just like in the demon island arc with anko, where naruto realized the toads couldn't help him because the kind of water wasn't right. whoever has the sharks summons would have to be mindful of what species they summon in what kinds of water. also the chakra amounts. smaller amounts of chakra could summon smaller species like maybe a juvenile lemon shark i imagine, while massive chakra reserves are required to summon someone like the great white.
but undeniably, they're useful. the electro-reception i think i mentioned earlier idrk, but sharks could, in that world, "see" the chakra flow of an enemy by sensing their electrical energy, since it technically stands to reason that chakra is a form of energy. so some would basically function like a low-level byakugan. and of course, sharks are used for long-range message delivery and tracking because they can go long distances (and fast like with the shortfin mako) and they can detect a drop of blood from miles away.
side note tho, for the shark sage mode, everytime i think abt it, all roads lead back to some traits from kisame. it makes logical sense. since what we saw with the toad sage mode, a shark sage understandably would gain features like gills, rougher skin for defense purposes. tho maybe, with the fusion of water and earth elements, the sage could like "swim" through solid earth, only to emerge out of the ground like a shark does with the water to like engulf their enemy. i think kisame did that actually. basically js a little like the jaws movie poster too. the giant jaws js under the surface abt to come up and eat the ppl, yk. OML and the eyes, the sage's eyes would go like pitch black (exactly like the hoppers movie, where that shark that planned to crush the car had its eyes go like fully black, yk yk) and they'd lose their emotions too. because sharks are largely prey-hunting animals, once someone goes into their sage mode, they'd become much more singularly focused, relentlessly fighting their enemy like they're prey. tho they'd wouldn't go so far as to be like gone mad abt killing their enemy, like the one tails possessing gaara.
shi sharks summons sounds fire asf. i can js imagine sicing a giant great white shark onto someone im fighting. like that dumbass in avatar that got dragged down into the depths of the ocean by a tulkun. idk abt genjustu tho, for sharks. maybe it'd be something like one of itachi's camouflaging techniques to blend in better.
