NAVY

1. Destroyers : They are the best ship for offense and defense against submarines they cannot attack land units like battleships and cruisers. They are decent against ships but I'd go with a submarine and battlehsips against ships and destroyers against a submarine.
2. Submarines: people think this is the best unit in navy and spam it a lot . It isn't true Submarines can be obliterated by destroyers in attack and defense so be sure to have destroyers . Subs are good against ships and subs idk about them against air cause people cannot see a sub unless it is attacking so no one really sent an airplane against my sub but cruisers should be used against air .
3. Cruisers: I'd sat it is the anti air of navy , you'll need them all time cause destroyers and subs can't attack land units and can't defend naval bombers while cruisers can attack land units and defend great against Bombers. However it is bad against other ships so definitely not your all navy .
4. Battleships: They are like really expensive and they can bomb land units more efficiently then cruisers just a better cruiser but really expensive and slow . They should be escorted by destroyers as it is bad against submarines . It is they key for winning a naval battle .
5. Aircraft carriers : self explanatory, it is a movable airstrip and cannot do anything else. So it must be escorted by other ships . It ia great if you have a good airforce that can turn the outcome of the battle .

Navy is a place which needs a stack you cannot have single units in it . Stacking up is essential to rule the seas . You can have better or other stacks but I use this : 2 destroyers . 2 subs , 3 to 4 cruisers , and 1 or 2 battleships that's about it I make aircraft carriers once my Frontline navy is done . I make more cruisers as I'm always lacking in airforce till day 6 or 7 after that u rule the skies as well .appvalley tutuapp tweakbox