Now that you have all eight badges, the following are now available: 
• Go catch the starters you didn't pick in Moirai. 
• The clerk on the top floor of the department store is selling new items. 
• Darkrai is catchable where you got Giratina. 

Before you head off to the Elite Four, here's a few things to keep in mind: 
• Grass and Ice are your best friends. A majority of their Pokémon are weak to these. 
• Giratina has a type advantage over the third/fourth members, so consider adding it to your party if you don't have a Ghost and/or Dragon type. 
• Make sure the Pokémon you plan on primarily using are Lv. 55+ by the time you're there. Otherwise you're gonna have a bad time. 

Route 666 

Pokémon:
Lv. 36-38 
Klink - 25% 
Mienfoo - 25% 
Rufflet - 15% 
Sigilyph - 15% 
Audino - 10% 
Druddigon - 10% 

Items:
Full Restore x1 
PPUP x1 
Sticky Barb 
TM04 
TM35 

Trainers: 
Juggler Jack - Sigilyph Lv. 40, Emogla Lv. 40, Leavanny Lv. 40 
Clerk Nelson - Klang Lv. 40, Sunflora Lv. 40, Lapras Lv. 40, Pinsir Lv. 40 
Clerk Trisha - Rufflet Lv. 40, Ariados Lv. 40, Floatzel Lv. 40, Rapidash Lv. 40 
Cool Trainer Kip* - Mienfoo Lv. 40, Jynx Lv. 40, Gloom Lv. 40, Banette Lv. 40, Kingdra Lv. 40 
Cool Trainer Lucca* - Druddigon Lv. 40, Vanillish Lv. 40, Swanna Lv. 40, Lampent Lv. 40, Sawsbuck Lv. 40 

You'll run into some trouble along the way, which will lead to your last battle with Aedus. 

Aedus 
Corsola - Lv. 50 
Weezing - Lv. 50 
Electrode - Lv. 50 
Forretress - Lv. 50 
Shiftry - Lv. 50 

Explosions everywhere. You'll save Alex, but who cares about that. What you should care about is the optional final battle with Leona at Granny's House. 

Leona
Delcatty - Lv. 50 
Liepard - Lv. 50 
Luxray - Lv. 50 
Persian - Lv. 50 
Absol - Lv. 50 

So he did give it to her after all! They sure do make nice punching bags. You'll also get a cute, little Meowth to add to your collection.

Victory Road 

Pokémon: 
Lv. 38-40 
Heatmor - 25% 
Durant - 25% 
Elgyem - 15% 
Golett - 15% 
Deino - 10% 
Skarmory - 10% 

Items: 
Ultra Ball x1 
Full Heal x1 
Full Restore x1 
Rare Candy x1 
Max Revive x2 
PPMax (Check rock) 
Nugget (Check rock) 
Dragon Fang 
TM75 
TM82 

Trainers: 
Psychic Micki - Girafarig Lv. 45, Beheeyem Lv. 45, Cohagrigus Lv. 45 
Psychic Alia - Wobbuffet Lv. 45, Xatu Lv. 45, Golurk Lv. 45 
Veteran Cathy - Durant Lv. 45, Omastar Lv. 45, Druddigon Lv. 45, Exploud Lv. 45, Jumpluff Lv. 45 
Veteran Zach - Heatmor Lv. 45, Kabutops Lv. 45, Dragonair Lv. 45, Toxicroak Lv. 45, Gigalith Lv. 45 
Nurse Mariah - Audino Lv. 45 
Blackbelt Lao - Mienfoo Lv. 45, Sawk Lv. 45, Crustle Lv. 45, Conkeldurr Lv. 45 
Battlegirl Xiao - Medicham Lv. 45, Throh Lv. 45, Steelix Lv. 45, Machamp Lv. 45 
Veteran Claude* - Skarmory Lv. 45, Rufflet Lv. 45, Rampardos Lv. 45, Magmortar Lv. 45, Venusaur Lv. 45 
Veteran Rayne* - Deino Lv. 45, Gastrodon Lv. 45, Ferrothorn Lv. 45, Armaldo Lv. 45, Infernape Lv. 45 

After traveling all the way around, stopping along the way to heal with the nurse, you'll get to have a battle with Emil one last time. 

Emil 
Klingklang - Lv. 52 
Electivire - Lv. 54 
Simisear/Simisage/Simipour - Lv. 54 
Umbreon - Lv. 54 
Nidoking/Nidoqueen - Lv. 54 
Starter - Lv. 55 

Hey, a full team. That's gotta be something. Too bad he doesn't give you anything. 

Pokémon League 

This is it. Time to show the world you're ready to become the next champion. Now there's some important things you should know. The fights are linear like in the older games, so the order will always be the same. Also, you'll notice Chanseys in the first room, the third room, and the final room. These will heal your Pokémon ONCE. If you leave the room, you can't go back, so you have the choice to either use it before moving on or not at all. If you want to challenge yourself, just ignore them. (What you see in parenthesis is hard mode.)

Elite Four - Nixie 
Politoad - Drizzle - Leftovers - Lvl 52 (55)
•Scald 
•Protect 
•Perish Song 
•Toxic 
Vaporeon - Hydration - Leftovers - Lvl 54 (56)
•Rest 
•Scald 
•Roar 
•Ice Beam 
Jellicent - Water Absorb (Cursed Body) - Leftovers - Lvl 54 (56)
•Water Spout (Will-o-wisp)
•Shadow Ball (Taunt)
•Scald 
•Energy Ball (Recover)
Cloyster - Skill Link - Leftovers - Lvl 54 (56)
•Shell Smash 
•Icicle Spear 
•Hydro Pump 
•Rock Blast 
Gyarados - Moxie - Leftovers - Lvl 55 (58)
•Dragon Dance 
•Waterfall 
•Bounce 
•Stone Edge 

Elite Four - Jorge 
Hippowdon - Sand Stream - Leftovers - Lvl 54 (56)
•Slack Off 
•Earthquake 
•Stealth Rock 
•Ice Fang 
Dugtrio - Arena Trap - Leftovers - Lvl 55 (58) 
•Substitute 
•Hone Claws 
•Earthquake 
•Sucker Punch 
Donphan - Sand Veil - Leftovers - Lvl 55 (58)
•Rapid Spin 
•Earthquake 
•Stealth Rock 
•Ice Shard 
Gliscor - Sand Veil - Leftovers - Lvl 55 (58)
•Earthquake 
•Toxic 
•U-turn 
•Protect (Roost)
Excadrill - Sand Rush - Leftovers - Lvl 56 (60)
•Swords Dance 
•Earthquake 
•Iron Head 
•Shadow Claw 

Elite Four - Alastor 
Espeon - Magic Bounce - Leftovers - Lvl 55 (58)
•Yawn 
•Psyshock 
•Shadow Ball 
•Grass Knot 
Alakazam - Magic Guard - Leftovers - Lvl 56 (60)
•Psychic 
•Focus Blast 
•Signal Beam 
•Substitute 
Reuniclus - Magic Guard - Leftovers - Lvl 56 (60)
•Calm Mind 
•Shadow Ball (Recover)
•Psychic 
•Focus Blast 
Starmie - Natural Cure - Leftovers - Lvl 56 (60)
•Surf 
•Thunderbolt 
•Ice Beam 
•Psychic 
Metagross - Clear Body - Leftovers - Lvl 58 (62)
•Meteor Mash 
•Hammer Arm 
•Zen Headbutt 
•Pursuit 

Elite Four - Melinda
Garchomp - Rough Skin - Leftovers - Lvl 56 (60)
•Dragon Claw (Outrage)
•Earthquake 
•Aqua Tail 
•Stone Edge (Dual Chop)
Dragonite - Multiscale - Leftovers - Lvl 58 (62)
•Dragon Dance 
•Dragon Claw 
•Fire Punch 
•Extreme Speed (Roost)
Salamence - Intimidate - Leftovers - Lvl 58 (62)
•Draco Meteor 
•Outrage 
•Heat Wave 
•Earthquake 
Haxorus - Mold Breaker - Leftovers - Lvl 58 (62)
•Swords Dance 
•Dragon Claw (Outrage)
•Low Kick 
•Aqua Tail 
Hydreigon - Levitate - Leftovers - Lvl 60 (64)
•Draco Meteor 
•Flamethrower 
•U-turn 
•Dark Pulse 

Champion
Blissey - Natural Cure - Leftovers - Lvl 58 (62)
•Wish 
•Protect 
•Toxic 
•Seismic Toss 
Jolteon - Volt Absorb - Life Orb - Lvl 60 (64)
•Thunderbolt 
•Volt Switch 
•Signal Beam 
•Thunder Wave 
Breloom - Technician - Life Orb - Lvl 60 (65)
•Low Sweep 
•Mach Punch 
•Bullet Seed 
•Spore 
Gengar - Levitate - Black Sludge - Lvl 62 (66)
•Substitute 
•Shadow Ball 
•Sludge Bomb 
•Focus Blast 
Mamoswine - Thick Fat - Life Orb - Lvl 64 (68)
•Icicle Crash 
•Ice Shard 
•Earthquake 
•Superpower 
Volcarona - Flame Body - Leftovers - Lvl 65 (70)
•Quiver Dance 
•Bug Buzz 
•Fiery Dance 
•Giga Drain (Roost)

Have fun!