I like the fact that you can get volt tackle, and the fact that a lot more of the pokemon's abilities can be used outside of battle. :) If you don't know what I mean, check this out:
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ABILITY CHANGES
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Emerald has also changed up the abilities a bit. In Ruby and Sapphire,
certain abilities (Pickup, Illuminate, etc.) only worked outside of
battle. But now, abilities can have both in and out-of-battle effects.
Note that these take effect if a Pokemon with these abilities is anywhere
in your party.
Flame Body
In battle: 30% chance of burning the opponent when attacked with a contact
move (Body Slam, Double Kick, Tackle, etc.)
Out of battle: Cuts egg hatching time in half.
Magma Armor
In battle: Pokemon cannot be froven
Out of battle: Same as Flame Body. Cannot be layered (you can't carry a
Magmar and a Numel and get 1/4 time).
Intimidate
In battle: Reduces opponent's attack by 50% when the Intimidator
switches in
Out of battle: Reduces low-level Wild Pokemon encounters
Keen Eye
In battle: Immune to accuracy modifiers
Out of battle: Same as Intimidate
Hustle
In battle: Increases damage by 50%/reduces attack accuracy to 80%
Out of battle: Increases high-level Pokemon encounters
Vital Spirit
In battle: Prevents all sleep effects (including Rest)
Out of battle: Same as Hustle
Pressure
In battle: Doubles PP used when attacked
Out of battle: Increases rate of Wild Pokemon encounters
Arena Trap
In battle: Opposing Pokemon cannot switch (does not work with Flying
types or Levitate Pokemon)
Out of battle: Same as Pressure
Suction Cups
In battle: Immune to the effect of Roar and Whirlwind
Out of battle: More likely to catch a Pokemon while fishing
Sticky Hold
In battle: Item cannot be taken by Thief/Covet/Trick
Out of battle: Same as Suction Cups
White Smoke
In battle: Immune to negative stat changes from opposing Pokemon
Out of battle: Lowers rate of wild Pokemon encounters
Sand Veil
In battle: When Sandstorm is in play, increases evasion
Out of battle: Reduces rate of encounters in Route 111 (Sandstorm
areas)
Static
In battle: 30% chance of paralyzing opposing Pokemon when hit with
a contact move
Out of battle: More likely to battle Electric Pokemon in the wild
Magnet Pull
In battle: Steel-type Pokemon cannot switch out
Out of battle: More likely to battle Steel Pokemon in the wild
(Heaven help the poor soul who goes into the Power Plant with
an Electrike and a Nosepass. He'll never want to see Magnemite
again.)
Synchronize
In battle: Status conditions inflicted on Synchronize Pokemon also
affect opponent
Out of battle: Increases the chance that a Wild Pokemon will have
the personality of the Synchronize Pokemon
Compound Eyes
In battle: Increases accuracy of attacks by 30%
Out of battle: More likely to encounter Pokemon holding items
Cute Charm
In battle: 30% chance of Attracting opposing Pokemon when hit
with a contact move
Out of battle: Increases likelihood that a Wild Pokemon will be
of the opposite gender of the Cute Charm Pokemon
Hyper Cutter
In battle: Immune to effects that lower the Attack stat
Out of battle: Increase the radius of Cut
Lightning Rod
In battle: Draws Electric-type attacks to the Lightning Rod Pokemon
Out of battle: Increases likelihood of phone calls with the Entry
Call
(Yes, you literally turn your Pokemon into a cell tower. If only
my provider could get new towers that easily).
Swarm
In battle: At low health, Bug moves do more damage
Out of battle: Increases the chance of hearing cries of wild Pokemon
One of the more broken parts of Ruby and Sapphire was that Pickup
didn't have any sort of control, so you could get Nuggets/Rare
Candies/Full Restores within twenty minutes of getting the Poke
Balls. Now, a system has been implemented where the quality of Pickup
goods depends on the level of the Pokemon using it.
Every time you fight a battle (except for the Battle Tube, and the
Pyramid has its own data), you have a chance to pick up an item. The
odds of picking up an item are listed below, in this format:
Common - 30% chance
Sometimes - 10% chance (each item)
Occasionally - 5% chance
Rarely - 3% chance
Very Rarely - 1% chance
Huge, HUGE thanks to Meowth346, who's got an information overload at
*link removed* (I found the raw data in the Abilities section):
L1-10:
Common - Potion
Sometimes - Super Potion, Antidote, Great Ball, Repel, Escape Rope,
X Attack
Occasionally - Full Heal
Rarely - Ultra Ball
Very Rarely - Hyper Potion, Nugget
L11-20:
Common - Antidote
Sometimes - Super Potion, Full Heal, Great Ball, Repel, Escape Rope,
X Attack
Occasionally - Ultra Ball
Rarely - Hyper Potion
Very Rarely - Nugget, King's Rock
L21-30:
Common - Super Potion
Sometimes - Great Ball, Repel, X Attack, Escape Rope, Full Heal, Ultra
Ball
Occasionally - Hyper Potion
Rarely - Rare Candy
Very Rarely - King's Rock, Full Restore
L31-40:
Common - Great Ball
Sometimes - Repel, Escape Rope, X Attack, Full Heal, Ultra Ball, Hyper
Potion
Occasionally - Rare Candy
Rarely - Protein
Very Rarely - Full Restore, Ether
L41-50:
Common - Repel
Sometimes - X Attack, Full Heal, Ultra Ball, Hyper Potion, Rare Candy,
Escape Rope
Occasionally - Protein
Rarely - Revive
Very Rarely - Ether, White Herb
L51-60:
Common - Escape Rope
Sometimes - Full Heal, Ultra Ball, Hyper Potion, Rare Candy, Protein,
X Attack
Occasionally - Revive
Rarely - HP Up
Very Rarely - White Herb, TM 44 (Rest)
L61-70:
Common - X Attack
Sometimes - Full Heal, Ultra Ball, Revive, Protein, Rare Candy, Hyper
Potion
Occasionally - HP Up
Rarely - Full Restore
Very Rarely - TM 44, Elixir
L71-80:
Common - Full Heal
Sometimes - Ultra Ball, Hyper Potion, Rare Candy, Protein, Revive, HP
Up
Occasionally - Full Restore
Rarely - Max Revive
Very Rarely - Elixir, TM 01 (Focus Punch)
L81-90:
Common - Ultra Ball
Sometimes - Hyper Potion, Rare Candy, Protein, HP Up, Revive, Full
Restore
Occasionally - Max Revive
Rarely - PP Up
Very Rarely - TM 01, Leftovers
L91-100:
Common - Hyper Potion
Sometimes - Rare Candy, Protein, HP Up, Revive, Full Restore, Max
Revive
Occasionally - PP Up
Rarely - Max Elixir
Very Rarely - Leftovers, TM 26 (Earthquake)