The skills list menu is pretty poor at explaining things isn't it (shock!

)
Auto-feint appears to work like this -
* makes basic skills all the same input and picks one at random.
* locks you out of the advanced skills completely
* BUT it makes intermediate skills much easier to do - because these are the ones that are most effective anyway that is why I believe most people will be perfectly fine keeping auto-feint on.
So, I'm sure you already know that the skills list changes depending on whether auto feint is on or off:
Auto-feint off
Auto-feint on
The only skills this causes a problem with is basic step-overs because for some reason they're all the same input!
As far as I can work out all 3 of these are done completely at random with auto feint on, unless a player has a specific trait such as 'multiple step-overs', in which case they'll always do that.
When you get to the intermediate skills however this is where auto-feint is really useful.
Take the 'Marseille Turn' as an example, instead of having to spin the right stick around, with auto feint on it's nothing more complicated than
View attachment 19685 on the right stick and
View attachment 19688 on the left stick.
All the other intermediate skills work in the same way; point the left stick one way, point the right stick another, and each combination will do a different skill. Simple. To learn which direction does what it's best to just work them out yourself with a bit of trial and error, and the skills list is horrible at explaining it.
In case you're worried on missing out on something by turning auto-feint on; the only skills you'll be locked out of are ones like the '3 touch roulette' like this:
It looks cool, but the animation is so long, and pressure is so powerful that it makes skills like this totally uneffective in 99% of situations anyway, so you're really not missing out on them.