Dustox hasn't got a very good range of moves really

but if mothmon attack dustox with Multiple Blaster attack, can dustox avoid with agile because he has the ability "Levitate", and if mothmon attack with Gauss Powder, Powder Gauss can dustox eliminate with the poison itself, mothomon can absorb the energy of other digimon, but dustox is not digimon
then if dustox attacked mothmon with "poisoned needle", mothmon run but with a heavy object on his tail, so mothmon only can fly by slow!

^ assuming Mothmon is slow. And 2 can play at this game, Mothmon can dodge poison sting even then since he's a digimon he won't get poisoned.

he has a Gatling gun.

I repeat. He has a Gatling gun. And it doesn't need bullets.

It can paralize its enimys as well as poison and put to sleep.