Well, let's just get this straight for other people who still get issues.
To pass the Start New file freeze, you need to have biosnds7.rom, biosnds9.rom and a firmware.bin on the same folder of your emulator, want them? Dump them from your DS.
The first bowser battle causes the screen to split and crash the emulator, making you lose your save file, so as soon as you can save with bowser, close the emulator, and make a copy of your .sav file.
How to bypass it: Before the battle disable the no$gba sound (it's the option where it will be either 22khz or 44khz). Before the battle starts, you'll see now that the logo won't split, BUT as soon as it is shown completely on the lower screen, enable the sound again or it will crash.
Later on, there's two other battles, with bricrok and a statue (they're both close to each other), the game freezes as soon as the HP box shows up.
How to bypass? Having no$zoomer version 2.3.0.2 (the real one) that on the "other" tab, there will be an option EXTRAS, select EX0 and EX5, if that doesn't do it, select all.
Now, the only issue I'm having is that the game runs slow, the EX5 really doesn't do nothing about speed, and also the save screen flickering already mentioned (which isn't a big deal) and sometimes the emulator crashes randomly (accusing that the rom image has failed, or something like it).
I would like, if possible, to know if there is anyway to play this game smoothly in the future =p
EDIT:
Btw, i think i'll start a new thread so people can find it easily, if possible, a mod delete this message.