The Cruiser is a Naval Unit that has multiple roles. In addition to attacking an enemy Submarine and Air Units, the Cruiser doubles as a transport, capable of carrying up to two Copter Units at one time.
In the original Game Boy Advance game, Cruisers were only capable of firing on Submarines with their Missiles, which were Anti-Sub Missiles. These are capable of causing devastating damage to a Sub, forcing it to retreat to port if it survives the attack.
Its secondary weapon was effective in its own right, as its Anti-Air Machine Guns could destroy an entire Copter Unit in one attack if the Cruiser has 10HP. This weapon also causes major damage to Fighter and Bomber Units as well.
From Advance Wars 2: Black Hole Rising onward, the Missiles of the Cruisers were modified into Anti-Ship Missiles. They still do massive damage to enemy Submarines, but also have the capability of attacking other Naval Units as well, which it couldn't do before.
When the enemy deploys a Submarine, no ships are safe without a Cruiser. The Cruiser serves as a counter-balance to the Submarine, so keep one at the ready in case the enemy starts to deploy Submarines.
In Advance Wars, Cruisers were also susceptible to taking serious damage from B Copter units, which would take heavy damage in return. This isn't the case in all the later games.
Until Advance Wars: Days of Ruin was released, Medium Tanks, Neotanks and a Megatank were all capable of causing significant damage to a Cruiser if it got within range, which isn't the case in Advance Wars: Days of Ruin.
Related ThreadsCruisers roooooooooock!!!!!!!!!!!!! - last post by @ May 26, 2008
Poll: Who actually loads their copters onto cruisers? - last post by @ Aug 27, 2013