Advance Wars: Dual Strike

Stealth Jet:
Pros: Turns invisible, fires at anything, can only be targeted by fighters and stealth jets when invisible.
Cons: Not quite as powerful as bomber/fighter, burns fuel fast.
Tactics: Invisibility is its strength. Use it to harass units near Anti-airs because they can't shoot you. Can also be used as a wall to block bridges and narrow corridors. Also useful against Carriers.

Pros: Ridiculously long range missiles, can carry aircraft.
Cons: Expensive, carried aircraft can't take off and move in the same turn.
Tactics: The best defence against air units. Just don't use them to carry anything unless you need to protect your planes from Cruisers.

Black Bomb:
Pros: Does 5 damage to everything in its blast radius (blast will not reduce a unit below 1 HP).
Cons: Expensive, one use only.
Tactics: Only to be used in the direst circumstances. Seems a waste of money imo.

Pros: Powerful and tough.
Cons: Slow, expensive, limited ammo and fuel.
Tactics: Only suitable for point defence. Too slow for assaults. Neotanks are better.

Advance Wars: Dark Conflict/Days of Ruin

Pros: Can retaliate against direct attacks, odd damage table, shoots helicopters.
Cons: Odd damage table, relatively expensive.
Tactics: The Anti-tank is the ideal unit for ground defence. It seems to take 25% damage from anything direct combat ground unit, and usually deals 50% back from full health. This does make it vulnerable to cheaper units like Recon, though, as they can cause a lot of damage for much lower cost. The Anti-tank is best used on the front line, where it can act as a solid wall to protect the more vulnerable Rockets. Trak is the most obvious CO to put in this, as his CO zone is wide enough to boost nearby Rocket attacks.

Still rubbish, although it is now a lot cheaper than before. Stick with Heavy Tanks. Lin in a Heavy can cripple a Megatank.

Pros: Air units can move on take off! Also repairs and refuels and builds Ship Planes.
Cons: Useless in combat.
Tactics: Basically a mobile tech airport that can hold two units and build Ship Planes (more on them next). Just keep it away from Subs.

Ship Plane:
Pros: Can shoot anything, reasonably powerful, great value.
Cons: Limited fuel and ammo.
Tactics: The ideal unit to defend your Carrier, as well as spearheading a coastal assault with Battleship backup. Putting Zadia in one of these makes it a force to be reckoned with. Be sure to keep it in range of your Carriers.