Rate my great league team?

I'd say replace the lanturn with azumaril, your team seems a bit more naturally suited to that rather than Lanturn. Azumaril's great as a wall to flygon's dragon claw spam, great water attacker, and your other two pokemon cover its weakness to poison and grass well, as well as flygon beign a hard electric counter.

I've run this exact team before, but the lack of TDO between the skarm and Flygon leaves them getting beat in neutral matchups and thus not covering each other too well. Maybe swap the flygon out for something beefier, since Lanturn and Skarmory cover each other pretty well already? And i'd TM steel wing for air slash, changes little in most matchups except for enabling you to beat medicham in a shield exchange and bodying meganium even more badly.

Granted, I run something similar but with Altaria as the dragon instead, which makes you weaker to melmetal but is better in neutral matchups, still beats lanturn, and gives you more options in switching since it can cover both the other two pokemon. Still just as weak to lapras as this team is, but slightly less vulnerable to azumarill.