Going along the same vein as Celebi, Shaymin can easily use a Life Orb set. I initially had Psychic because "beating Heracross and Roserade was cool," but Leech Seed has saved my ass so many times, and if I have to, I can hit both with HP Fire. And yea, I had Leech Seed AND Rest. As usual, I'll take comments for other moves, but I'm obviously only going to initially put what I used.
http://www.smogon.com/dp/pokemon/shaymin
[SET]
name: Sweeping Shaymin
move 1: Seed Flare
move 2: Hidden Power Fire / Hidden Power Ice / Hidden Power Ground
move 3: Leech Seed
move 4: Rest
item: Life Orb
nature: Timid
evs: 32 HP / 252 SpA / 224 Spe
[SET COMMENTS]
<p>Shaymin's purpose here is to use its 320 Speed to systematically wreak utter havoc on the opponent's team with Seed Flare and its 40% chance to lower the opponent's Special Defense by 2 stages. Leech Seed is chosen because it gives Shaymin the upper hand against Blissey and Snorlax and their massive HP. Rest is to heal off residual Life Orb recoil damage and any damage Shaymin might accrue throughout battle.</p>
<p>The choice of Hidden Power depends entirely on what Shaymin must beat. Hidden Power Fire is a nice complement to Leech Seed, and helps Shaymin beat Steel Pokemon like Skarmory and Bronzong. Hidden Power Ice can be chosen if Garchomp and Salamence are issues and Shaymin must absolutely defeat them. Hidden Power Ground is for Heatran and Houndoom, who resist Seed Flare + Hidden Power Fire / Ice.</p>
<p>Timid is chosen to allow Shaymin to outspeed all +Speed nature base 90 Pokemon like Roserade and Lucario, and all +Speed nature base 95 Pokemon like Gliscor and Kingdra. Modest can be chosen if outspeeding those Pokemon is less important than the added power. 32 HP EVs reach 349 HP, the perfect number for a Life Orb set, which yields 11 uses of Life Orb, as opposed to 10. Also noteworthy is that Shaymin's Natural Cure ability allows it to heal the Sleep status (along with any other status) when it switches out, meaning it can Rest with little to no concern.</p>
http://www.smogon.com/dp/pokemon/shaymin
[SET]
name: Sweeping Shaymin
move 1: Seed Flare
move 2: Hidden Power Fire / Hidden Power Ice / Hidden Power Ground
move 3: Leech Seed
move 4: Rest
item: Life Orb
nature: Timid
evs: 32 HP / 252 SpA / 224 Spe
[SET COMMENTS]
<p>Shaymin's purpose here is to use its 320 Speed to systematically wreak utter havoc on the opponent's team with Seed Flare and its 40% chance to lower the opponent's Special Defense by 2 stages. Leech Seed is chosen because it gives Shaymin the upper hand against Blissey and Snorlax and their massive HP. Rest is to heal off residual Life Orb recoil damage and any damage Shaymin might accrue throughout battle.</p>
<p>The choice of Hidden Power depends entirely on what Shaymin must beat. Hidden Power Fire is a nice complement to Leech Seed, and helps Shaymin beat Steel Pokemon like Skarmory and Bronzong. Hidden Power Ice can be chosen if Garchomp and Salamence are issues and Shaymin must absolutely defeat them. Hidden Power Ground is for Heatran and Houndoom, who resist Seed Flare + Hidden Power Fire / Ice.</p>
<p>Timid is chosen to allow Shaymin to outspeed all +Speed nature base 90 Pokemon like Roserade and Lucario, and all +Speed nature base 95 Pokemon like Gliscor and Kingdra. Modest can be chosen if outspeeding those Pokemon is less important than the added power. 32 HP EVs reach 349 HP, the perfect number for a Life Orb set, which yields 11 uses of Life Orb, as opposed to 10. Also noteworthy is that Shaymin's Natural Cure ability allows it to heal the Sleep status (along with any other status) when it switches out, meaning it can Rest with little to no concern.</p>