Androxus's high mobility and hitscan weapon give him significant advantages. You can try to lure him to a confined space to limit his mobility and make your weapon easier to hit with, and use Dead Zone to restrict his ability to heal.
Once an Andro tries to flank you, you should try to get one or two shots on him, then use your seedlings. He will most likely use reversal which gives you time to escape. This works best if Andro's escape ability is on cooldown (after he has flied)
If Androxus tries to flank and kill you, be careful where you shoot. If he uses Reversal, you can try to shoot behind him and use splash damage to kill him since reversal only takes damage from the front and Androxus can't shoot while in Reversal.
Never use seedling for androxus he can reversal up to 3187.5
If he is flying try to make him go near the wall so you can shot him easier
Try to note facing him 1vs1