I think Biggie's influence was more about general execution than it was just as rhyming. The way that he was talking about gritty, violent, drug dealing street topics over such poppy beats and familiar samples was unprecedented for the most part - at least in terms of how it was done. Mo Money Mo Problems had a familiar Diana Ross sample while Biggie's talking about the feds tapping his phone. Dr. Dre and Snoop were doing it too, but Biggie did it and was able to pair it with the really hard-sounding stuff too.
That leads into the other thing. Life After Death is a blueprint that rappers still follow today, in terms of how it blatantly reaches out to serve different demographics with different songs - romantic songs for women, hard songs for street dudes, street songs, party songs, songs for the West Coast, songs for the Midwest, etc. - and actually do it so well.
As far as his actual influence rhyming, tough for me to pinpoint it at the moment