Lupin Sansei: Pandora no Isan/Stage 3

The docks

 * In the first section of stage 3, you must overcome a number of jumps and obstacles to make it to the warehouse on the right side of the stage. Who you choose to start out on this mission is a matter of preference.  There are a number of barrels that roll through here, making Goemon a good choice.  However, if he falls in the water just once, he's finished.
 * On the other hand, as long as you have oxygen tanks, Lupin can survive a slip in the water. In fact, while he's down there, he may happen to discover items floating through the water.  Each section of water typically contains three particular items that appear repeatedly.  However, if you're not seeing oxygen tanks or bullet-proof vests, don't spend much time in those sections.  Climb out and continue on above the water surface.
 * You'll encounter typical warehouse goons at first, but later on in the game, you will encounter a type of hunched over enemy that wields a knife and likes to hop. Shadow ninjas will also pop out of the water.  But the hardest enemy to deal with may be the mortar firing soldiers.  Jigen can take them out from a safe distance.  Otherwise, time your passage through their shots and attack them when it's safe.  If you find them too difficult, you may also consider swimming under them as Lupin.
 * In addition to enemies and hops over gaps, you must watch out for platforms that rise and fall on lifts. Make your jumps carefully to reach the other side.  Near the end of the stage, you will notice mechanical objects that float near the top of the stage.  They can make jumping a hazard, but they are easily destroyed.  Remove them before you attempt to continue to the end.

Warehouse interior

 * The warehouse is composed of four floors. Although you must alternate directions as you proceed through the warehouse, each floor is, for all intent purposes, fairly identical to one another.  There is a little variation in the enemy occupants, but nothing significant.
 * On each floor, you must run from the entrance on one side to the exit on the opposite side, taking out enemies as you encounter them, and exploring each of the doors that you pass. Some of the warehouse goons tote guns around, but their range is roughly the same as Lupin's and they are slow to fire.
 * Shadow ninjas will also hop out of the water to fight with you. Keep looking behind every door to search for items, and potentially rescue captured partners.  Depending on who you are, you will begin to hear rumors about a "lady boss" and a "relic" in a pyramid.
 * In addition to the goons and more barrels, you will encounter a new type of enemy, a hunched over brute. One bullet won't take them down.  If they get hit, they flash red and speed up with anger.  It takes three more bullets to knock them out.  However, one slice of Goemon's sword is also enough to silence them.
 * You will also encounter another floating mechanical object. Unlike the ones outside, these are black, and they are impervious to bullets.  You can destroy them with Goemon's sword, or use a bomb.
 * By the fourth floor, you should consider switching to Lupin and activating the goggles so you can see where the infrared trap triggers are and avoid them. You'll want to make it to the end with Jigen uncaptured and available to fight.

Boss
Rald is apparently a giant robot that shoots energy from his eyes. This fight is very much like the first fight. You can pin the boss against the right wall with Jigen while he fires from a safe distance on the left. However, setting up this fight can be a little tricky. It's a good idea to start out with Lupin. Presumably, you have some bullet-proof vests, and Lupin can take a hit or two until it's safe to bring Jigen in. As Lupin, jump on the first row of boxes near the entrance. This will line you up to hit Rald in the head with your gun. After you have successfully pushed Rald far enough away from the entrance, switch to Jigen, and have him stand on the left edge of the box while he continues to pelt Rald with bullets. Jigen will not be out of harm's way here. If Rald fires energy straight across, Jigen must duck to avoid getting hit. Then stand right back up when the energy passes him and continue firing. Once you hit him enough, the real Rald will actually fall out of the robot, and inform you that a "lady boss" instructed him to kidnap Clarisse, and that they've gone to a pyramid.