Blaster Master Final Boss Strategies

Blaster Master Final Boss Strategies
by ZeroNoin

The final boss of Blaster Master (the armored guy with a whip and shield) is easy to exploit.  Positioning your character and/or spamming grenades can make this boss trivial (except perhaps for some difficult mashing).  Again note that your character moves 1.5 pixels per frame.

-Mechanics-

Boss Attributes
This boss has 192 Hit Points and 16 I-frames, so this fight takes a long time regardless (grenades and full gun power do 2 damage, so at least 25.3 seconds).  His shield cracks at 127 HP (2/3 HP), and his shield disappears at 63 HP (1/3 HP).  His body and whip each do 64 damage (2 bars of health), meaning you can endure up to 3 hits during this fight, and 4 hits is always death.  There is almost never lag during this fight.  This boss's movement seems to respond to the tile position of your character, meaning that his movements respond to 16-pixel increments (0 to 15) in your X position, and 16-pixel increments (0 to 15) in your Y position.

Tile Positioning
Since this boss's movements respond to the tile position of your character, your pixel position within a tile increment will tend to determine your specific position relative to the boss.  Basically, when your character moves from one tile position to another, the boss's positioning shifts 16 pixels in the same direction; moving your character as many as 16 pixels, and as few as 1 pixel, can suddenly shift the boss 16 pixels.  When the right side of your character lines up graphically with the first X pixels in a tile here, your X tile pixel position is 0; your X tile pixel position is 0 when you enter the boss room; the higher your X tile pixel position, the closer you tend to stand to the boss.  Your Y position is at the bottom of your character's feet; you are at a Y tile pixel position of 0 when the bottom of your character's feet graphically line up with the first Y pixels of one of the leftmost or rightmost tiles; the higher your Y tile pixel position, the farther you tend to stand from the boss.  This boss's whip direction is likely also related to tile position.

Right Wall Positioning
If you stand next to the right wall with an X tile pixel position of 13 to 15, and a Y tile pixel position of 7 to 15 (excluding the top of the room), once the boss reaches the right wall, he very rarely will hit you; the RNG pattern needed for him to hit you is very unlikely.  The wall prevents him from getting into a position where his whip will hit you, and the wall prevents him from walking on you.  You can line your character up to be even, or slightly left of even, with the tile on the bottom wall, or use the dots in the floor to position; the rightmost position has a X tile pixel position of 4, meaning 5 to 7 pixels is the proper distance from the rightmost X position.  Keep in mind, unless you are in the bottom right corner, he can still potentially whip you as he first transitions over to the right wall.  You can use tiles in the very right wall to set a good Y tile pixel position; having the bottom of your character's shadow, or the top of your character's head, lined up with (or close to) a gap in one of these tiles works for safe positioning; the bottom of the room has a Y tile pixel position of 8.  See images below for more specific information.

Above Positioning
If your character's feet are not positioned lower than this boss's feet, his AI will not try to whip.  If your character is near the top of the screen, the boss cannot move high enough to be in a position to try to whip you.  If your character faces downward from the top Y position in the room, your downward grenades will still be high enough to hit the boss.  If your X tile pixel position is 11 to 15, the boss will almost always be in a position where vertically-fired grenades will have an X position that hits the X position of this boss; the RNG pattern needed for him to more away briefly is very unlikely.

Invincibility Frames
This boss has 16 I-frames; he can be hit again on the 16th frame following being hit.  In addition to colliding with your attacks, colliding with your character sets off his I-frames, meaning 16 frames of time are loss when his body hits yours.  During his I-frames, his body's hitbox and hurtbox are inactive, meaning he cannot be hit, and his body cannot hit you; keeping his body's hurtbox inactive creates an interesting strategy where you can continuously stand on top of him.  Hitting him precisely every 16 frames will prevent you from being hit by his body; but because your normal gun bullets do not linger long, and your grenades have only 9 straight frames when they are active to hit things, attacking faster will be necessary; grenading evenly every 9 frames (about 6-2/3 times per second) will keep his body's hurtbox inactive, but because your presses will not be so even, mashing more like 8 times or more per second will be necessary; if you really need a short mashing break, you can Pause for a moment (though you probably should have used a different strategy).  You can reposition your character while standing on this boss without being hit as long as you continue hitting him.  These I-frames do not apply to his whip.

-Strategies-

Right Wall Strategy
As the boss of Area 8 explodes, use the right wall positioning described above, facing upward.  As he moves toward you, spam grenades until the boss dies.

Right Wall Bottom Strategy
As the boss of Area 8 explodes, face upward and hold A.  Move to the bottom right corner, the very bottom, your character's back centered, or slightly left of being centered, on the rightmost full tile (see right wall positioning above).  As he moves toward you, spam grenades until the boss dies.

Top-Right Strategy (with Grenade Mash)
As the boss of Area 8 explodes, face left and position graphically about 2 or 3 tiles from the right wall, and about 2 or 3 tiles from the top of the room.  When the explosions end, start spamming grenades.  The boss will move toward you.  About the time the boss's body overlaps yours, turn to face up while still spamming grenades; hold Up and tap right a few times as needed to get into a position where the right wall prevents him from moving out of your grenades, release the directional pad, and spam grenades until the boss dies; if you position about 2 tiles from the wall at the start of the fight, tapping right may be unnecessary.

Top-Center Strategy (with Grenade Mash)
As the boss of Area 8 explodes, from the centered X position, tap Left to move 1 to 5 pixels left of center, then face down and hold A and move all the way to the top of the room.  When the explosions end, start spamming grenades.  If the positioning is wrong, while still spamming grenades, hold Up and tap right to move right a few pixels, or perhaps keep tapping right to move into the corner, then release the directional pad.  Continue spamming grenades until the boss dies.

Strategy Comparison
The top screen strategies require good mashing, and are going to be about 2 seconds faster as they hit the boss from the start of the fight; the top-center strategy is easier, but very rarely will lose some frames if the boss happens to move away briefly; the top-right strategy often will lose frames during the transition, from grenade misses and/or I-frames triggered from colliding with your character's body, but does not lose frames if executed well.  The middle right wall strategy is about 1 second faster than the bottom right strategy, but you might get hit by a whip near the start of the fight; mediocre mashing (about 4 presses per second) is typically only about a second slower than fast mashing for these; it is possible to hit the boss as he transitions over the right wall, but it does not seem worth the trouble; the right wall strategies are much easier and less risky, good for racing or those who have trouble mashing.

Demonstration Video - https://youtu.be/xBoaby3aKxo
Bottom-Right 13 and 15 X Tile Pixel Position Images - http://i.imgur.com/1UYQ6Gl.png
Right 13,7 15,7 13,15 15,15 Tile Pixel Position Images - http://i.imgur.com/Y2OG5GP.png
Top-Center 11 and 15 X Tile Pixel Position Images - http://i.imgur.com/k6Ct7Jr.png

Credits
Not sure who to credit for many of these strategies, likely UraniumAnchor and ShiningDragoon among them.
I found the Top-Center Strategy, tile-positioning information, specific pixel values, and various other specific information.
I also made the video and images.

End