This is literally a loser faggot mentality. The fun of Mega Man is tackling the stages however you want and slowly improving as well as eventually gaining more powers to help you conquer the rest more easily, and using knowledge on weaknesses etc. to make later playthroughs more smooth and satisfying. Thinking you NEED the 'ideal path' from the very beginning is very, very pussy loser behavior and just looking it up ruins half the fun of the series.

Besides, in most of the megaman games your default weapon works well, or well enough, on multiple bosses, ESPECIALLY the like, 90% of the series where you have the charge shot that works equally well on all bosses, and various boss weapons work at least fairly well on various other bosses, not just the main weakness. These games are very well-designed so that you can never feel 'stuck' and rarely feel like you truly "picked completely wrong" to an insurmountable degree. Unless you suck ass, of course.