Leveling all Kaiju questions?

[Taliesin_2943]

Ok I'm at a point where that's basically all I have left but I don't fully understand how to do it effectively like with Godzilla all I have to do is play through get points cause there's no real strategy he's just easy but with the others they require specific stuff to them to level up and it seems like every run is random on what I fight

 

So the question is is there a specific method to getting the parts required for each without the guessing and randomized stuff? I'm especially concerned about the ones that they spawn so rarely that getting parts is a crap shoot and I know I have to play as those Kaiju so how would I fight there doppelganger or can the parts only be gotten as a different Kaiju?

 

Like is there a guide anywhere explaining how this all works?