It also depends on the CP range of Dragonites + their moves, but I guess he can take down at least 2 Dragonites at around 3000CP Up 0 Down
I usually can take down 2+ 3000+cp Dragonites with my Lapras (he's 2200cp with IS/B). I dodge a bit more because of IS but he does the job very well. Up 0 Down
Dodging quick attacks you could take out 3. Mine is 200 less cp with the same move set and 3 is pretty common as long as they don't have DT Up 0 Down