The mode of each Pokemon's BST, including alternate forms, is 600, and the median is 458.

The mode for HP is 60, Attack is 100, Defense is 70, Special Attack is 40, Special Defense is 50, and Speed is 50.

The median for HP is 68, Attack is 77, Defense is 70, Special Attack is 65, Special Defense is 70, and Speed is 65.

Source: Copying the table from this page into a Google spreadsheet and then taking two minutes to learn how to use functions to find the median and mode of a column.