I already have the Pokémon you're offering, but wanted to share a tip. If you ever want to catch Landorus and complete the Unova Dex, you need to keep or "borrow" Tornadus and take it and Thundurus to Abundant Shrine to interact with its shrine. Afterwards, you can return Tornadus to its owner if (s)he wants it back. Landorus comes at Lv.70.