Berries, they help your Pokémon in battle and help raises their contest status. The Berries are only obtainable through Wild Pokémon, a Berry Man or by Trading with Ruby/Sapphire/Colosseum.
Here you will find a list of all the berries and what they do:

Picture: Number: Name: Effect: Location:
#01 Cheri Berry Heals Paralysis S.S. Anne/Pick-Up Ability
#02 Chesto Berry Heals Sleeping S.S. Anne/Pick-Up Ability
#03 Pecha Berry Heals Poison S.S. Anne/Pick-Up Ability
#04 Rawst Berry Heals Burn Pick-Up Ability
#05 Aspear Berry Heals Frozen Status Pick-Up Ability
#06 Leppa Berry Recovers 10PP to an attack Pokémon Jump Prize
#07 Oran Berry Recovers 10HP Pick-Up Ability
#08 Persim Berry Heals Confusion Pick-Up Ability
#09 Lum Berry Heals Any Status Condition Pokémon Jump Prize
#10 Sitrus Berry Recovers 30HP Pokémon Jump Prize
#11 Figy Berry Recovers 1/8 HP and confuses any Pokémon that doesnt like Spicy Flavour Pokémon Jump Prize
#12 Wiki Berry Recovers 1/8 HP and confuses any Pokémon that doesnt like Dry Flavour Pokémon Jump Prize
#13 Mago Berry Recovers 1/8 HP and confuses any Pokémon that doesnt like Sweet Flavour Pokémon Jump Prize
#14 Aguav Berry Recovers 1/8 HP and confuses any Pokémon that doesnt like Bitter Flavour Pokémon Jump Prize
#15 Iapapa Berry Recovers 1/8 HP and confuses any Pokémon that doesnt like Sour Flavour Pokémon Jump Prize/Berry Forest
#16 Razz Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#17 Bluk Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#18 Nanab Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#19 Wepear Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#20 Pinap Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#21 Pomeg Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#22 Kelpsy Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#23 Qualot Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#24 Hondew Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#25 Grepa Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#26 Tamato Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#27 Cornn Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#28 Magost Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#29 Rabuta Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#30 Nomel Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#31 Spelon Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#32 Pamtre Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#33 Watmel Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#34 Durin Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#35 Belue Berry Plant in the Earth to grow Berries for Pokéblocks Dodrio Berry Picking Prize
#36 Liechi Berry Raises Attack when HP is below 1/3 Ruby/Sapphire
#37 Ganlon Berry Raises Defense when HP is below 1/3 Colosseum
#38 Salac Berry Raises Speed when HP is below 1/3 Colosseum
#39 Petaya Berry Raises Special Attack when HP is below 1/3 Colosseum
#40 Apicot Berry Raises Special Defense when HP is below 1/3 Colosseum
#41 Lansat Berry Raises Critical Hit Ratio when HP is below 1/3 Emerald
#42 Starf Berry Raises Any Stat when HP is below 1/3 Emerald
#43 Enigma Berry Morphs into E-Reader Berries Ruby/Sapphire

 
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