Tuning bass to match the guitars?

quite often i tune the e string on guitar flat too because of hard hitters.
I always do this very slightly on my guitar, it's just always sounded better that way.

My little brother plays the double bass and if he's plucking and i'm jamming along i always get him to detune the bottom string slightly as the peak of the note is always way sharp.

Ultimately, use your ears, do what sounds best (Y)
 
i was under the impression that tracking bass after guitars was to make sure the tone worked with the guitars, not so much to make sure the tuning is the same. Guitars and bass should be in tune no matter whn you record them. You can always autotune the bass in the end if it's slightly off.