Very few bus drivers are good at driving bi.
You probably meant to say "good at driving bōs" (accusative case of second declension masculine plural) (when you are driving something, it is accusative case, not nominative)
So here it is, corrected version:Very few bus drivers are good at driving bōs.
One can also notice that the word "driver" has an ending matching one of the second declension masculine patterns, so we can further improve your sentence:Very few bus drivī are good at driving bōs.
Naturally, why stop there if we still have undeclined word of "bus" in the beginning of the sentence? We can easily turn it into genetive masculine plural!Very few drivī of bōrum are good at driving bōs.
Now we are left with one more undeclined word: driving. "good at driving" is clearly a locative case. Sadly though, there is no Latin declension for words that end with -ing...