Guide to Tekkyuuman bosses, by Kleme

Good reader,

first and foremost I must admit my surprise that you've found your way to this guide. This indie game, Tekkyuuman, is not very well known and does not have big communities around it.

Tekkyuuman (Iron ball man) is a simple, short indie platformer game with some really well made physics. 
Since the stages are simple, and of only a single screen each, it does not make much sense to write guides for each stage individually but when it comes to the boss fights (four of them in total), there is some strategy to be discussed.

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The 1st boss (Stage 3) is very RNG heavy when it comes to killing him as fast as possible. This is due to Tekkyuuman attacking at various speeds depending on the distance of the target, and being at the optimal attacking distance of the 1st boss is lethal after the boss gets up from the initial jump to the stage. After the boss is up you must stay at the 2nd best distance from it and if the boss decides to move too much towards you you will either get hit and die, or have to back away too much and miss the one-cycle kill before boss does charge attack due to not being able to land enough attacks.

- To quickly defeat the 1st boss one must align the head of Tekkyuuman with the mountains on the background, close to where the boss lands after the jump. Given how optimal your position is, you can get 9 to 10 hits in before boss gets up and is able to land a first hit. After the boss is up you must stay as close to the boss as possible, without getting hit, while repeatedly attacking at him. If done optimally, you will kill the boss before he does the first charge attack. Extra time save for hitting the sporb (spiked orb) while it's in air, still falling down.

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The 2nd boss (Stage 6) is not dependant on RNG when it comes to killing him as fast as possible. At first you must land attacks from behind while dodging two grenades and at the right window, during boss transitioning to machine gun phase, jump over him and hit him in the back until he dies.

- To quickly defeat the 2nd buss one must align Tekkyuuman by the "window" in the background, in the 
middle of the stage. From there throw your iron ball pre-emptively to hit boss once from behind, then repeatedly jumping and throwing your iron ball behind the boss as many times as possible while also dodging the two grenades he throws, after the second grenade throw you have time for one more hit before you have to jump over him when he is about to start shooting with machine gun. Hit the back of the boss until defeated. Extra time save for hitting the sporb while it's in air, still falling down.

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The 3rd boss (Stage 9) is the easiest of the bunch. With correct positioning you can throw your iron ball behind the boss, let it automatically hit the boss, let the boss teleport behind and dash towards you then jump to dodge the dash and throw a new iron ball while landing, rinse and repeat until boss is dead.

- To quickly defeat the 3rd boss one must align Tekkyuuman slightly to the right from the center of the stage. Throw your iron ball when boss is falling down from the initial jump, when boss teleports behind you and dashes jump to dodge the attack and throw a new ball while falling down. If done optimally you will need to get four iron balls thrown behind the boss in total (including the one thrown when boss is initially jumping to the stage) but if this four-cycle kill is missed you can just do a fourth jump+throw combo to finish boss off. Extra time save for hitting the sporb while it's in air, still falling down.

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The fourth and final boss (Stage 12) is the longest fight and, just like the 1st boss, RNG heavy. The boss has four different phases it goes through and each one requires a tactic of it's own to survive and complete optimally.

o In the first phase the boss throws his basket up in the air and fireballs rain down. During this time the boss can be freely hit with no lashback.

o In the second phase the boss charges a little while on the other side of the stage and then charges towards you. The boss can be hit during this time but will instantly kill you if he gets too close. To avoid getting hit you must do a wall-jump at the sides of the stage to get above the boss and to the other side. Boss will charge three times in total.

o In the third phase the boss will stop at the left-side of the stage and starts shooting two types fireballs from his back basket. First type of fireball will travel by the floor and must be jumped over while the second fireball is bouncing and should be dodged by letting it bounce over you. You can find a spot close to the right of the boss where you don't have to move away from to easily dodge the first type of fireballs by jumping and then stand still to dodge the 2nd type. Fireballs are always shot in same order, type 1 > type 2 > type 1 > type 2 and so on.

o In the fourth phase the boss will do exactly the same charges as in phase two but starting from opposite side of the stage. Boss will, again, charge three times in total.

- To quickly defeat the 4th boss one must align Tekkyuuman at the center of the stage, facing left-side. After boss has jumped on to the stage and is about to enter the first phase you pre-emptively throw your iron ball to the left and run to the right-side of the boss. This will allow you to focus on dodging the fireballs while continuously attacking the boss. When the strikes of your first iron ball throw are about to end get close to the boss and while repeatedly attacking the boss move to the left-side of him. When you see the basket falling down step away from the boss and prepare for the second phase. 
In the second phase you should try your best to jump and throw your iron ball behind the boss when he does his first charge. After this you do not have time to turn around and throw your iron ball when boss is doing the second charge so you must throw your iron ball forward while running around the center of the stage, jump over the iron ball when it returns and let it hit the boss that is chasing you. Repeat this for the third charge. 
If the boss is still alive when entering the third phase, you should find and move to the spot closest to the boss where you can stand still to dodge bouncing fireballs and only jump to dodge the fireballs that move on the floor. Try to get as many hits in as possible, duly note that you will have to jump in this phase to dodge every 2nd fireball and if you jump over the returning iron ball you will lose time so try to practice the throws so you always catch them right away as they return to you. 
If the boss is still alive after this phase you will do the same tactics as with the second phase but starting from the other side of the stage.

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And that's about it! All except for the fourth boss are simple, and even the fourth boss will become simple once you understand the phases, but easy to mess up at the heat of the moment. I'll do my best to grind down the WR of this game and any competition will be gladly welcomed :) Do not hesitate to throw me a message here at speedrun.com or PM me in Discord, I'm happy to talk about this lovely little game and anything related to it!

Yours,
Kleme