>>96343920
As someone who plays at a store with at least 3 bracket 4-5 Y'shtola decks a week, Y'shtola can be very threatening if built with the Curiosity/Lifelink combo, but she absolutely folds if you try to cast her without protection. Being a 4 drop that you need to invest mana into to get things like Curiosity effects or Lifelink means you're basically playing a psuedo voltron strategy with drain instead of commander damage as a wincon.
With that being said she is an amazing commander if there is someone more threatening at the table to pull the attention off of you long enough to build your pillow fort.
>>96343828
As for the answer to the question, her precon is not really workable, it want to do too much that she doesn't really support, in all honesty the actual deck she comes with feels better suited to the Cat Boy alt commander than for Y'shtola herself, Y'shtola wants things like Buyback spells or cost reduction cards (think Jet Medallion or the like) alongside big flashy spells that stax our your opponent until you hit something like Bolas's Citadel/Omniscience and cast your entire library for Lethal
