[rg111]

It is more like Nyaya-Vaisheshika was the only school that could barely confront Buddhism.

And Sankara had many ideas that were similar to Buddhism, like disdain for rituals, liberation through knowledge, disregard of caste hierarchy, etc.

He was later attacked by rival Vedanta schools for being opposed to rituals as rituals are central to the Vedas.

But he did attack Buddha and Buddhist ideas. The point of conflict was the existence of self.

But he used many strawman arguments, and criticised Buddha for saying things he didn't say. Sankara didn't know and didn't care.

He was a great philosopher, though.

[jaldhar]

That’s a rather tendentious way of putting it. There was a vigorous back and forth between the Nyaya and Buddhist logicians as acknowledged by thinkers on both sides. And barely or not, Nyaya did eventually prevail.

Shankaracharyas problems with Buddhism are because he was criticizing something that had already ceased to be a living vigorous tradition in his time.