Is seed flare good in Pokemon?

Yes, Seed Flare is a VERY good move. It has a natural 40% chance of lowering the foes Sp. Defense 2 Levels. (Effectively halving it) This is even better when Shaymin is in Sky Forme, because of Serene Grace (Shaymin Sky Forme's ability) this % doubles to 80% chance. This basically guarantees a Sp. Defense drop. Not to mention the Base Power! (120)