Certain mechanics in Advance Wars: Dual Strike are not completely explained in-game. This guide aims to quickly help the reader learn how these mechanics work. (There are certain omissions, including describing Skill and Ranks.)
Damage calculation[]
Here is a formula describing the damage inflicted to a defending unit.
In addition, if a direct attack unit fails to destroy a unit that can attack it, the defending unit uses the formula to attack the attacking unit. Black bomb and Oozium do not counterattack.
Fuel, ammo, money, and healing[]
Each Com tower increases the atk boost of the owning CO pair by 10%. Com towers do not give money.
Fuel is reduced per move space based on the terrain and the type of unit per the "Effects" table in Terrain (default is 1/space). With 0 fuel, units cannot move. For air units, fuel is instead reduced by a unit-dependent amount per day. Submerged submarines and stealthed stealth fighters consume more fuel. With 0 fuel, air and naval units are destroyed. Attacking and counterattacking uses 1 ammo of the applicable weapon.
Headquarters, cities, and factories heal 2 HP and fully supply ammo and fuel to land units. Ports do the same for naval units. Airports do the same for air units. Healing at buildings costs 10% the cost of the unit per HP healed (e.g. 30% with Rachel's ability).
Unknown: If you can't afford to heal all units at bases, which ones are healed?
COs and CO powers[]
Commanding Officers (COs) have a passive effect, a CO power, a super CO power, a number of stars required to use the CO power, and a number of stars required to use the super CO power. The first three are described roughly in the in-game CO info. The fourth and fifth can be seen based on the size of the stars during a match on the top info screen. All can be found on the CO pages.
The effects of CO powers and tag breaks end when your opponent's next turn ends.
Charging powers[]
Initially, it takes 50 star points to charge a star. When the active CO's unit is damaged, the CO gains star points based on the unit type per the "Star Points for Units" table here. (Note the table shows star points gained per 10 HP lost.) When the active CO's unit inflicts damage, the active CO gains half as many star points. The inactive CO always gains half as many star points as the active CO.
Every time you use a CO power, super CO power, or tag break, the number of star points per star for the relevant CO(s) increases by 10 until it's 140. After that, the star points per star is 100 forever.
CO pairing bonuses[]
Some CO pairings have 1, 2, or 3 stars - increasing luck by .05, .10, or .15 (not just during tag breaks). You can see which COs a particular CO has stars with in their CO info screen. You can also find the number of stars on the CO pages.
Some CO pairings have an attack boost while the tag break is active. For example, Jake and Rachel have a 0.20 = 20% boost. 120% is shown on the screen when the tag break starts. You can find the atk boost amount on the CO pages.
Submarines and stealth planes[]
The opponent cannot see a submerged submarine or stealthed stealth fighter (the AI will ignore them too). If the opponent attempts to move through or onto the submerged/stealthed unit's cell, they stop next to the submerged/stealthed unit and their turn ends (without performing an action). The submerged/stealthed unit is visible to the opponent only while it is over an opponent's building or next to an opponent's unit (it still remains submerged/stealthed). The submerged/stealthed unit can only be attacked when visible. Submerged submarines can only ever be attacked by cruisers and other submarines (submerged or not). Stealthed fighters can only be attacked by fighters and other stealth fighters (stealthed or not). Submerged/stealthed units still take damage from sources other than units (e.g. CO powers, missile silos).
Damage from sources other than units cannot reduce any unit's HP to less than 1.