So, since the sub 15 run is out, there's some points I want to put, in case anyone want to run and get a similar time.

Making the Character:

What only matter are the Power and Speed gauges. You will only need those ones to proceed during the run. Stamina will grow up by its own when picking up Training Items. Defense is really useless and you won't need to raise it, but you'll need to be careful to take too many hits or else you'll get down easily.

First Fight and Knockdowns RNG:

Every starts needs to be against Mick Llonigan (use the Reset Cartdrige option for that), and here's where it'll be decided if you'll get a good run or not.

Aparently, the most important RNG in the game is the Knockdowns. Knockdowns looks random but during the Career Mode, once you defeat the first opponent with a certain number of knockdowns in a single round, all of them will be the same. So, if you defeat Llonigan on the first round with 2 knockdowns, all of the subsequent opponents will follow the same pattern.

And that's why Llonigan's fight is the most important one for the run. Here you'll need the fastest pattern, which is defeating with only a knockdown. 2 knockdowns or TKO will get a lot of time for you, so if Llonigan get up on the first knockdown, you reset.

So keep a reminder that you'll reset some times before you get the fastest pattern for the Career Mode.