First, there is a low chance that Naruto can even summon Gambunta. You need huge chakra + chakra control. Naruto had no control over Kuruma's chakra, keep in mind it was leaking. Without chakra control, summoning Gambunta would be very difficult.
Second, let's say he does summon Gambunta. CM Level 2 Sasuke is like a fly to Gambunta. Gambunta won't be able to cause any damage to Sasuke because Sasuke is way too small and with wings Sasuke is way too agile.
Third, Chidori powered by Natural Energy is enough to do critical damage to Gambunta and cause him to desummon.
