The incipit of a piece on the IDF from Ynet:
Alexander the Great, the man who conquered the ancient world, said that those who develop new combat methods or who possess new arms will be triumphant.
Did he ever say such a thing?
Alexander Quote?
quidquid bene dictum est ab ullo, meum est
rogueclassicism 
It seems very unlikely. I couldn’t find a reference, though you can never safely be dogmatic about a negative.
If Alexander believed such a thing, then he would have adopted elephants into his order of battle after he faced Poros.
The “quote” looks to me more like an inaccurate rendition of something the military theorist General J.F.C. Fuller said, concerning what he called the Constant Tactical Factor.
It’s sort of implied by Curtius 7.7.15, where Alexander suggests that the Macedonians have so far been victorious through “war skills/arts”, of which his example is the crossing of the Oxus on straw-packed hides. But he worries that the locals will imitate such tactics.