You can win without Reviver Seeds, it's just really hard (I've done it). Sleep Seeds are good. Dig is a must; it's awesomely effective. You can pick up TM Dig in Treeshroud Forest. Bring Oran Berries if you can. You probably already know this, but Roar of Time is incredibly powerful. If it hits you, eat an Oran Berry right away, and give one to your partner if you can. It took me a while, too, but Primal Dialga is not unbeatable.