GHOST 1.0

A a couple of tips that helped get through the harder bosses. I did this all on NG++ so by the final stage all my skills were maxed out, and nothing was truly difficult by the end.

During the rescue mission, use the Energy gun and don't bother firing your main weapon after the boss puts up the shield. Movement is key during this fight and using the regular gun will only slow you down. The Energy gun will bypass the shield, and it should take about 6 shots with it to defeat the boss.

For the final stage, a level 5 Cloak Gun, Beam Drone Gun, and Shortcut Wave Gun will make this easy. Cloak up, once that expires, use the Shortcut gun to stun everything one screen and run around to get your Cloak charged back up. Use the Beam Drone gun when possible as that will fire 4 lasers that hit everything on screen, meaning you don't have to worry about aim. Combined with the Missile Gun and Dragoon Frame the final fight isn't that hard, just keep an eye out for the cluster bombs some enemies drop when defeated.