You forgot to mention that this team won the #pokemon tournament! Anyways I really enjoyed using it. There are just a few things I'd change but they're more of preference changes rather than necessities.
I think it'd be worth trying out Spikes Roserade over Amoonguss. You lose some bulk, but Spikes are really helpful, and Natural Cure is really cool for shrugging off status, mainly burns from Rotom-W / random Scalds. Spikes | Giga Drain | HP Fire | Rest should work well.
I would also go with Rock Polish > U-turn and a Modest nature on Landorus. U-turn is nice in theory but I never found myself using it, whereas I can recall a few situations where I had a free turn that wouldn've been an easy win if I had the option to double my Speed. Timid nature really isn't outrunning anything of note and the extra power from Modest is really appreciated.
Overall, this is a very solid team, well done man.