Don't play Partners in Time.
It lacks the exploration of the other games and the babies add nothing to the game except serve to overcomplicate things. It's not nearly as funny as the other games, either, unless you find babies crying (and crying and crying and crying) hilarious and the villain is uninteresting.
It's playable, but it's bland and dull as dishwater. Only play it if you really don't want to skip any game in the series.