Pāṇini was probably the only man I would say was comparable to Einstein in intelligence.
Any discussion of outliers in intelligence that mentions Einstein but not Newton is simply missing a difference of several standard deviations.
It is not obvious to me that, across the total number of human minds produced so far, an outlier like Newton has any reasonable probability of existing.
Some authors have suggested that he likely used his students minds as "scratch pad" to hold temporary ideas expressed as succinct verses.