I’ve never looked into Gatorade powder and so don’t know what that starting point is. I’m familiar with the content of the Gatorade drinks though and really and truly, that product is a matter of key marketing principles executed well. These principles include “It’s better to be first than to be better.”
The first brand in a category usually becomes and remains the market leader. What’s the difference between Tylenol and other brands of acetaminophen? It’s the identical substance, identical dosing, identical really in every way but brand name. The difference is, Tylenol was first.
Advil? The first ibuprofen brand to enter, still the leader decades later. Again, no actual difference in product.
Gatorade was the first sports drink and that, combined with competent follow-up marketing and a big ad budget every year, is why it is the market leader. The reason isn’t that it’s better than any run of the mill stuff.
Unless having it on hand already, I wouldn’t see a reason to start with it. 1/4 tsp of salt and 1/4 tsp of “light salt” (potassium chloride) and there are your electrolytes. Or 1/2 tsp of a salt that is already a premix of the two. Glucose can be purchased at the health food stores; maltodextrin isn’t hard to order. Actually there are many grades to maltodextrin and differing properties with regard to how easily it dissolves, but for a basic effort that shouldn’t be too much of a deal. If you use only glucose that would be fine for lower carb content such as up to about 50 g/L, but for higher carb content it would be desirable to combine with maltodextrin or use maltodextrin only.
As for the leucine, 5-10 g of total leucine content. If using BCAA’s, 10-25 g. At the higher amounts there would be no need to add separate leucine as well.
You’d still be short on having a hydrolyzed protein.