Hi @Vasanth, welcome to the forum 
We generally use 4S batteries (the higher voltage provides some extra thruster torque), but 3S is still comfortably within the operating range of our non-5V electronics, and 16Ah is a decent capacity. 25C discharge with 16Ah capacity allows for a current of 400A.
One of our T200 thrusters at the nominal 3S LiPo voltage of 11.1V would draw ~15.5A at maximum thrust (from the performance specifications on the product page). The standard configuration BlueROV2 has 6 thrusters, so 6 x 15.5A = 93A, which is well within that 400A limit. The BlueROV2 heavy configuration uses 8 thrusters, so 124A max, which is also well within that limit, with plenty to spare for powering the other electronics.
It’s worth noting that LiPo and LiIon batteries often have two discharge ratings - one for continuous discharge, and one for burst discharge (for periods under 10 seconds). If possible I’d recommend confirming that your 25C rating is continuous rather than burst, and if it’s not then you can do the same calculations for the actual continuous rating
If it turns out that your battery has a lower continuous rating than your thrusters would be expected to use at maximum thrust, you can likely still use it but you’ll likely need to look into limiting the thrust output.