Frank Karsten Ive mentioned eight minimum sources of each primary color, but these numbers should clearly show you why skimping on this is usually a bad idea
Furthermore, the fact that we technically cannot attack with the leader if we want to take advantage of its effect to rest an opponent's card means that in the end we have to make the most of this effect or we will be playing at a disadvantage against the opponent who can attack with his leader while using its effects
Listen, I understand this guy is overstating his card blah blah, regrade and that is trash and all, this isnt really about that
To help in your training, the book starts with a how-to guide to understanding knitting patterns, then explains and demonstrates the various stitches needed to make the Pokmon
However, @deku made me check my own, as I wasnt aware of the specie error