All battle mechanic changes in Hacker's Memory

The following data comes from a combination of the officially-licensed V Jump Books Hacker's Memory guide, translating from Japanese to English, and from direct evaluation of the Japanese and English games.

No Digimon stats were changed in the transition between Cyber Sleuth and Hacker's Memory. Instead, changes were made to all three Skill types, Inheritable, Special, and Support, as well as to equipment slots. Certain Digimon have had SP costs reduced for some Specials, their chance of inflicting secondary effects increased, or even entire abilities replaced. This list only covers changes to existing Digimon, not new Digimon introduced in Hacker's Memory, and focuses on Perfect, Ultimate, and Super Ultimate-level Digimon.

General mechanic changes

• The Neutral Inheritable Skills (Power Energy/Heavy Strike/Mach Rush) now have the "Always Hits" property, ensuring that every Digimon can now have a counter to evasion-based strategies.
• On status effect duration; Confusion ends after 2~4 turns, Paralysis after 3~5 turns, Sleep after 1~3 turns, Stun after 1 turn, Poison after 3~4 turns, and Dot after 2~4 turns. Support nullification after 5 turns. All status buffs end after 5 turns, while all counter skills end after 3. Digimon can now act on the same turn that they wake up from Sleep.
• The maximum Ability is now 200, rather than the 100 of the first game. This puts the maximum number of bonus stats at 150.
• Most Digimon with Piercing Specials have had their Attack/Intelligence multiplier reduced, and their descriptions do not specify how large the multiplier is. Instead they call the output damage "medium," (中) "large," (大) or "heavy/extra-large." (特大)
• Most Digimon with standard damaging Specials have seen either a +5 or a +10 buff to that Special's base power. A few examples can be seen under "Special Skill changes."
• Unless otherwise mentioned below, any Special Skill that inflicts a status effect has now had its probability to inflict it raised or lowered to make that probability exactly 40%.

Inheritable Skill changes

• Dispel and Restore now cost 25 SP rather than 8. This serves to more strictly limit one of the most popular strategies from the late Cyber Sleuth's metagame; using Dispel to shrug off the Attack decrease incurred by using Shine Greymon: Burst Mode's Final Shining Burst.
• Seven of the status error moves have been reduced to 70% accuracy instead of 100%: Texture Blow, Panic Wisp, Shock, Venom Trap, Idle Bubble, Ripping Net, and Character Reverse.
• Support End is the only status move to retain 100% accuracy.

Support Skill changes

• #324 Magnamon's Miracle now has a 10% chance of reducing damage by 75%, instead of reducing damage by 30%.
• #219 Alphamon's Hermitic Loner now increases the damage dealt to Royal Knight Digimon by 50%, instead of 20%. This puts it on a level playing field with the new Counterattack, Armagemon's Support Skill.
• #249 Shine Greymon: Burst Mode's Shining Burst now increases the damage the party receives from magical attacks by 50%. Previously the Support increased the damage from Dark-attribute attacks by 25%. The Attack increase from the Skill is still only 25%. This is likely in reaction to how overwhelming Burst teams were late in Sleuth's life.
• #150 Aero V-dramon & #220 Ulforce V-dramon's Swiftness now only affects the user.

Special Skill changes

• #168 Skull Greymon's Oblivion Bird now has a 50% chance to reduce the target's Defense by 10%, instead of a 30% chance.
• #191 Black King Numemon's Dark Pupil now has an 80% chance to inflict Poison, not 20%.
• #192 Blue Meramon's Cold Flame now always buffs their Intelligence by 10%, rather than having a 10% chance to do so.
• #200 Mega Seadramon's Lightning Javelin now has an added 40% chance to Paralyze.
• #205 Metal Tyrannomon's Nuclear Laser now always increases their Defense by 10%, instead of having a 30% chance to do so.
• #207 Monzaemon's Lovely Attack/Hearts Attack was originally a Piercing Neutral Special that ignored the target's Intelligence and had a 10% chance to Stun. Its cost has been reduced from 30 SP to 20, and it has been changed into a restorative Special that heals one ally for 50% (singleplayer) or 10% of their maximum HP (multiplayer) and increases their Attack, Defense, and Intelligence by 10%.
• #211 Rapidmon (Perfect)'s Golden Triangle now has a 10% chance to increase all of their base stats by 10%, instead of a 5% chance to do so.
• #212 Lilymon's Flow' Cannon/Flower Cannon now has an added 50% chance to Paralyze.
• #213 Lucemon: Falldown Mode's Dead or Alive has had its base power increased by 20.
• #216 Were Garurumon (Black)'s Engetsugeri/Full Moon Kick now always increases his Speed by 10% instead of having a 10% chance to do so.
• #219 Alphamon's Seiken Grandalpha/Blade of the Dragon King has been changed to a single 150 physical Light-attribute hit to one enemy. Formerly it dealt 3~6 Light-attribute physical attacks to one enemy, with each hit having a base power of 30.
• #220 Ulforce V-dramon's Shining V Force/The Ray of Victory now always increases their Speed by 10%, instead of having a 10% chance to do so.
• #221 EBEmon's Brain Rupture has had its chance to inflict Confusion raised to 50%, from 20%.
• #227 Venom Vamdemon's Venom Infuse/Venom Infusion has had its chance to inflict Poison raised to 50%, from 30%.
• #228 War Greymon's Brave Tornado/Great Tornado now says it deals "large" damage rather than "double," and the attribute has been changed from Fire to Neutral.
• #230 Gaioumon/Gaiomon's Rinkazan/Will-'O-Wisp Slash now deals two 70-power hits, not 65.
• #236 Kuzuhamon's Taizoukai Mandala now always hits regardless of accuracy.
• The cost of #237 Gran Kuwagamon's Dimension Scissor has been reduced from 40 SP to 35 SP, and it now deals "large" damage, not "double." Further testing needed.
• #242 Cherubimon (Vice)/Kerpymon (Black)'s Lightning Spear now deals "large" damage, not "double." Further testing needed.
• #249 Shine Greymon: Burst Mode's Final Shining Burst now decreases their Attack by 50% after use, instead of 10%, and its accuracy has been reduced to 90%.
• #250 Justimon's Justice Kick has its probability to buff all stats by 50% raised to a 5% probability, from 1%.
• #257 Titamon's Konpaku Shingeki/Soul Core Attack has had its SP cost reduced from 40 to 30, and now deals "large" damage rather than "double." Further testing needed.
• #259 Dianamon's Good Night Moon has had its base power reduced from 125 to 120, and its chance to inflict Sleep reduced from 100% to 50%.
• #262 Dukemon's Royal Saber/Lightning Joust has had its chance to increase Defense by 10% raised to a 50% probability, from 30%.
• #263 Dynasmon's Dragon's Roar now deals two hits of 60, not two hits of 55.
• #265 Duftmon's Ernste Welle/Black Aura Blast now decreases the opponent's Defense by 20% instead of 10%.
• #272 Banchou Leomon's Flash Banchou Punch/Flashy Boss Punch has had its chance of inflicitng Stun reduced from 75% to 50%.
• #273 Piemon's Trump Sword now inflicts the Support End status error.
• #274 Pinocchimon's Bullet Hammer/Puppet Pummel has had its chance of incliting Stun raised to 50%, from 25%.
• #276 Black War Greymon's Dark Gaia Force/Dark Terra Force now decreases the opponent's Attack by 20% instead of 10%, and Black Tornado deals "large" Dark-attribute damage, not "double." Further testing needed.
• #277 Prince Mamemon's Smiley Warhead/Smile Warhead has had its base power reduced to 110, from 130. In exchange, it now always inflicts Knockback.
• #280 Herakle Kabuterimon's Giga Blaster now has a base power of 130, not 120.
• #282 Beelzebumon: Blast Mode's Chaos Flare/Corona Destroyer now deals "large" Dark-attribute damage, not "double." Further testing needed.
• #283 Belphemon: Sleep Mode's Eternal Nightmare now deals "medium" Dark-attribute damage. Further testing needed.
• #285 Holydramon's Holy Flame/Fire Tornado now has a base power of 95, formerly 80.
• #297 Metal Garurumon has lost the Garuru Tomahawk Special, which has been replaced by Cocytus Breath. Cocytus Breath costs 20 SP, deals 115 Water-attribute magical damage to a single target, and has a 25% chance to Paralyze. #298 Metal Garurumon (Black) retains the Garuru Tomahawk Special.
• #299 Metal Seadramon's Ultimate Stream/River of Power now has a base power of 130, not 120.
• #301 Rust Tyrannomon's Terrors Cluster now has a 50% chance to inflict Paralysis, not 25%.
• #303 Lilithmon's Phantom Pain now deals "heavy" damage, not "triple." Direct testing demonstrates that the exact multiplier for her Intelligence is now 2.5x instead of 3x.
• #306 Lord Knightmon's Argent Fear/Fist of Athena has had its SP cost reduced from 50 to 40, and deals "heavy" damage not "triple." (Same wording as the new Lilithmon.) Further testing needed.
• #313 Imperialdramon: Paladin Mode has had its chance to inflict Dot raisedto 30%, from 10%.
• #314 Examon's Pendragon's Glory now deals 145 Wind damage rather than 135. 
• #315 Omegamon's Garuru Cannon/Supreme Cannon now deals "large" Intelligence-Piercing Water-attribute damage to one foe. Previously it dealt 130 Water-attribute magical damage to a single target; the old version of the Special is retained by Omegamon NX.
• #316 Omegamon Zwart's Garuru Cannon/Supreme Cannon is the same as the new Omegamon's.
• #321 Belphemon: Rage Mode's Gift of Darkness has had its SP cost reduced from 60 to 40, and now deals "heavy" Dark-attribute damage to one foe, not "triple." (Same wording as the new Lilithmon.) Further testing needed.
• #322 Lucemon: Satan Mode's Divine Atonement has had its SP cost increased from 30 to 50. It now deals 200 magical Light-attribute damage to all foes, and decreases the user's Intelligence by 50% if it hits. Its accuracy has been reduced to 90%. Previously it dealt 105 Light-attribute damage to all foes.
• #323 Fladramon's Knuckle Fire/Flaming Fist has had its base power increased to 70, from 50.
• #324 Magnamon's S-Gold Solar Storm now increases their Defense by 15%, formerly 10%.
• #325 Rapidmon (Armor)'s Golden Triangle now has a 20% chance to increase all of their basic stats by 10%. Previously the description stated it always worked.

Equipment Slots
Almost all Perfect-level and equivalent Digimon now have 3 equpiment slots. The exceptions are;

• Atlur Kabuterimon, Aero V-dramon, Zudomon, Whamon, Monzaemon and Magnamon are unchanged from the previous game. All of them have 2 slots except for Aero, who has 1.
• Cyberdramon, Metal Greymon, Metal Greymon (Blue) and Lucemon: Falldown Mode all gained another slot, putting them at 2.
• Garmmon and Omega Shoutmon are newly introduced, but only have 2 slots.

In kind, many of the Ultimate and Super Ultimate-level Digimon have 3 equipment slots in Hacker's Memory. The following 56 Digimon have less than 3 equipment slots.

• Arkadimon Ultimate, Alphamon, Ulforce V-dramon, Chaos Dukemon, Craniummon, Sleipmon, Dukemon, Beelzebumon, Belphemon: Sleep Mode, Mastemon, Leviamon, Armagemon, Alphamon Ouryuuken, and Susanoomon have 1 slot.
• Imperialdramon: Dragon Mode, Imperialdramon: Fighter Mode, Valdurmon, War Greymon, Ophanimon, Kaiser Greymon, Chaosdramon, Gankuumon, Gran Dracmon, Cherubimon (Virtue), Goddramon, Jesmon, Shine Greymon, Shine Greymon: Burst Mode, Slayerdramon, Seraphimon, Tyrant Kabuterimon, Diablomon, Demon, Dynasmon, Durandamon, DORUgoramon, Neptunemon, Pile Volcamon, Barbamon, Black War Greymon, Breakdramon, Beelzebumon: Blast Mode, Holydramon, Megidramon, Mercurymon, Lilithmon, Ravemon: Blast Mode, Lord Knightmon, Arkadimon: Super Ultimate, Imperialdramon: Paladin Mode, Examon, Omegamon, Omegamon Zwart, Dukemon: Crimson Mode, Belphemon: Rage Mode, and Lucemon: Satan Mode.
• The remaining 50 Ultimate and Super Ultimate-level Digimon have 3 slots.