I think this is extremely insightful, as you’ve always been, Zita.
While many pitchers are going to have a traditional arsenal of fastball/change/curve and be effective that way, I think it is important to note that if you happen to find a pitch that is absolutely filthy that you can definitely build everything else off of it, even if it is a breaking pitch.
I would advise most youngsters to begin by working on fastball change, to be able to develop that fastball, as that will more than likely carry you further than anything else if you are looking to break into the collegiate or professional ranks.
That being said, not everybody starts pitching young, and not everybody will fit that traditional mold. While I played baseball since I was young, I didn’t start pitching until I was in high school, and it was solely because I was so interested and intrigued in the knuckleball that one day my coach saw it and was like “woah” and started working with me on pitching. My fastball and pitching mechanics in general were very lacking and far behind my peers. But boy could I make a baseball flutter.
So I found that I could pitch throwing a lot of knuckleballs, with the fastball being my change of pace to blow by an unsuspecting batter who was expecting that slow fluttering knuck and had only seen that from me. It wasn’t particularly fast, but compared to my 55mph knuck, it sure looked fast. This would turn into a mind game of, when is the fastball coming? and get batters really on their toes.
I mixed a curve in now and then, but I built my whole style on a breaking pitch, the knuck. I wouldn’t advise everyone do that, in fact I’d advise against the knuck most of the time for youngsters. But Zita’s right, you can absolutely be effective without basing your repertoire on the good old fashioned fastball and change.
But if you don’t have anything to base off of yet, I would follow fearsomefour’s advise and roll with fastball/change above all else, and if you do find another niche with a less common pitch, don’t be afraid to base your style off of it or mix it in, whether it becomes a swing and miss pitch, a pitch to contact/strike throwing tool or a change of pace type of thing.