As you make your way into the shrine you will find TM35 Flamethrower. Near the Youngster there is a Razor Fang.
If you have both Tornadus and Thundurus (you will have to trade one from the other game) then you can go up to the shrine to make Landorus appear.
If 30 turns pass, you can use a Timer Ball for the best chance of catching Landorus. Otherwise, if it's night time, you can use a Dusk Ball. If you don't have that, try using Ultra Balls.
TM92 Trick Room
Surf across the water east of the shrine to find TM92 Trick Room.