Go back to all the optional areas you might have missed earlier, like Route 211, Wayward Cave, Amity Square, Lost Tower, Solaceon Ruins, Maniac Cave, Route 213, Fuego Ironworks, Route 221, and Iron Island
Explore Turnback Cave, Snowpoint Temple, and Route 224
Explore the Battle Zone (the landmass northeast of the mainland) and defeat all the trainers there
Obtain every Poketch app
Defeat all VS seeker trainers after catching Heatran
Defeat Cynthia 20 times and then defeat your rival
Get all 14 foreign language Pokedex entries
Defeat 100 trainers in a row in the Battle Tower, both singles and doubles
Win every master rank contest
Obtain the platinum flag
Complete the national Pokedex. You can find non-Sinnoh Pokemon with the dual slot, Poke radar, outbreaks, super rod, the Underground, Great Marsh, and Trophy Garden. There are specific Pokemon you can find in other places, like Eevee, Rotom, Giratina, Regigigas, and Cresselia.
Obtain as many different items as possible
Obtain as many different ribbons as possible
Obtain as many different secret base items as possible
Obtain as many different accessories and backdrops as possible
Max your Pal Park score
Pick up all (non-regenerating) hidden items
Max your trainer card score
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