Combine our tactics with that of your own and face down the beast! I would suggest, however, that you bring two bag slots full of Reviver Seeds (16, in other words). If you get through the Hidden Land, the Hidden Highland, Temporal Tower, AND Temporal Spire without using a Reviver Seed, you are either cheating or are a miracle worker. In any case, try to get to Dialga without using many Reviver Seeds. Then you'll have a much better chance and a much bigger safety net.