note that there are spoilers ahead. only read if you are stuck. i will not be including Seekers, since most of them become regular enemies after you fight them for the first time.
Boss 1: Bounty Hunter
Location: Aurelian City
Attacks: Twin Handguns, Jet Pack, Hover platform, melee attacks
Details: you meet this boss after a short fight in the Aurelian City. the platform you fight on is a narrow brigde with plenty of space to fall off. you and your opponent will start off on opposite sides of the bridge.
as soon as the fight starts, the Bounty Hunter will immediately begin plugging away at you with his hand guns (these hurt quite badly). Negate works to deflect most of the bullets, but it's a good idea to crouch because some of the bullets can go under the shield, causing damage. once you get close enough, he will stop firing. don't worry about attacking him for now, he has a shield, which deflects ALL attacks, including melee. just stay near him and avoid his melee attacks as best you can, hitting him every so often to throw him off the edge (he will get back on using his jet pack).
after a while, he will jump in the air and cause an explosion along the ground. just watch the Hunter and listen for the whine of his jet pack, then time your jump to avoid the explosion. once he lands again, he will be vulnerable to your attacks. punch him off the edge, and run back to the large area of the bridge. the hunter will pop back up on a hover platform and begin firing missles at the main bridge.
as soon as he comes over to your side of the bridge, target one of the engines on either side and destroy it using any weapon or power. Aeon Pulse works well. as soon as you destry it, he will fly back over to the area of the bridge he started at. get there as fast as you can, or you might get shot by his guns.
repeat until the cut scene starts.
Boss 2: Skin Walker
Location: the Sky Cannon area, after you free Marin
Attacks: Charge, rocks will fall from celing, throws a large rock right at you, various punching and smashing attacks
Details: this fight is relatively simple, if you know how to hurt the Skin Walker. the Walker is impervious to all attacks, including Powers and Weapons.
just keep moving and avoiding his attacks until you see him pick up a large boulder and hold it over his head for a few seconds. at this point, you should either Lift the rock and drop it on his head, or use Surge and make him drop it himself. once you have done this, he will fall over and allow you do deliver a beating to his head. melee attacks are the only thing that really work.
repeat until the cut scene starts.
Boss 3: Ethan/Olivia
Location: after the credits, in front of the Galactic Counsel
Attacks: Throws rocks, gusts of wind, a large black orb, a large explosion, Seekers will help
Details: this boss is an interesting one. you actually choose who you fight very early on in the game, as you are getting on the espace pods to go to the planet. if you choose to save Olivia, you will fight Ethan. if you save Ethan, you will fight Olivia.
all you have to do is dodge the attacks that Olivia/Ethan throws at you (except the gusts of wind, those are undodgeable. they do very little damage though). once you see them charging a black ball, get ready for some ping-pong (Zelda, anyone?). make sure you have surge equipped. as soon as Olivia/Ethan throws the ball at you, puch it back using Surge. you don't have to charge it. do this until they fall to the ground.
some golden rocks will drop from the celling. Lift one, and throw it at Olivia/Ethan. you will know if you hit them or not because they will get back up. after they get up, be prepared to fight a few Seekers.
repeat until the cutscene starts. after you start fighting them again, simply pull the right trigger.
Level 4B Mario Pipe
There are Mairo Warp Pipes hidden throughout the game, one of which is in Chapter 4, Level B. To reach it, you must hit 6 switches:
Switch 1: From your starting point there is a black object on the wall in front of you. If you blow it up, the first switch will be revealed.
Switch 2: Continuing through the level, you pass under a large gun, ad then walk into an open area with 3 more black objects. Blow up the one in the corner opposite the area's entrance, and the second switch is revealed.
Switch 3: From the location of the second switch, go up the small ramp and wait for 2 bridges to appear. Each bridge is on one side of another large gun. Do a charged jump from the bridge to a platform above the gun. There is a hidden room here which houses the 3rd switch and an enemy.
Switch 4: If you continue through the level, you will come across an area where enemies spawn from 3 doors: 2 small ones on your right and a large door in the distance. The large door leads to a tunnel (for a reference point, the door is under a turret), which contains the 4th switch.
Switches 5 & 6: Continue through the level until you reach a point where you must hit a switch to create a bridge. Make the bridge and begin walking down it. While walking across the bridge, look to your right, and you will see an alcove with 2 more large explosive objects in it. Blow both of these up to reveal the final 2 switches. Hit the switch closer to the beginning of the bridge first, as they must be ht in order through the level.
A previously locked door is now open at the end of the bridge, and the pipe is now accessbile.
Advent Rising Staff Room
This secret is located in Chapter 4 - The Awakening - Part E. Through this level there is a series of three buttons which much be activated in this order...
Button 1 - In the room with the three shock troopers the first button, as you enter the room, is on the back of the right top portion of the area that holds rocket launchers in about the middle. You may have to tilt the camera upward to see this area. Destroy the black object to reveal the first button.
Button 2 - In the room after you fight the two Seeker Elites, go to the locked door and do a charge jump to the area above the door. There is a button on the ground all the way at the end of this area. Destroy the black object first.
Button 3 - Right before you meet up with Enorym in the room with the dead Aurelian. Jump to the bottom, below the platform, and go to the furthest column in the back to find a button behind it.
Backtrack to the previous room, and a new door is unlocked. Go inside to find the Advent Rising staff room complete with pictures of the AR staff by each console. Activate the consoles inside the room in this order to get an image of a ninja wailing on a guitar in the middle of the room...
Console 1 - guy with the white guitar
Console 2 - guy with the black-rimmed glasses
Console 3 - guy with the wooded background
Console 4 - person with the long black hair
Console 5 - guy with mustache and beard
Console 6 - guy holding up the "Utah County Sheriff" sign
Console 7 - guy with spiky hair and glasses (Donald Mustard)
After acquiring the Charge Jump ability, you can do an inifinite jump. It really isn't very useful, but you can reach som insane heights. To do this, target an enemy and charge the jump (hold X+A) until it is fully charged, then release and instantly begin tapping B repeatedly. Normally tapping B once would cause you to do a powerful melee attack downward that sends out a shockwave when you land, but instead you'll keep going up until you stop tapping B. Also, this doesn't seem to work unless you fully charge the jump.
Hit these buttons on the pause menu and a menu of 4 cheats uber mode,god mode,unlimited ammo (this includes unlimited power meter), and Blizzow
Up, Up, Down, Down, Left, Right, Left, Right, White, Black, X