Elements

Just like every other Megaman series, there are weaknesses and strengths to attacks. In the Battle Network franchise, there is a set of elements that are attached to chips and viruses. In the first three Battle Network games, there are 5 elements: Fire, Aqua, Elec, Wood, and null, or no element. If a viruses element was weak against a chip used, the virus will take 2x damage. As the series progressed, more elements were added. This was needed because in the 4th and 5th editions of the game (Battle Network 4 and 5), the double soul ability that replaced style change requires the sacrifice of a chip of the same element as the double soul being used. At the end of the series in Battle Network 6, there are a total of nine elements. All the elements and their attributes are listed below. Strong against Wood, weak against Aqua.
 * Fire/Flame

Abilities

Wildfire: If a virus or navi is standing on a grass panel, fire attacks do double damage regardless of the attribute of the Navi/virus. (all games)

Lava immunity: Fire attributed Navis/viruses do not take damage from lava panels. (BN 1,2,3,4)

Lava absorb: While using Firesoul, Megaman will recover 50 HP every time he steps on a lava panel, but this turns the panel back to normal. (BN 4 only)

Styles(MMBN 2,3)

A fire attribute style will have the prefix "Heat"

Souls(MMBN 4 and 5)

Firesoul(Fireman) obtained in MMBN4 Red Sun

Napalmsoul(Napalmman) obtained in MMBN5 Team Protoman

Crosses(MMBN 6)

Heatcross(Heatman) obtained in Gregar version

Chargecross(Chargeman) obtained in Gregar version

Bosses

Fireman.EXE (BN1, BN4 Red Sun)

Bombman.EXE (BN1)

Heatman.EXE (BN2, BN6 Gregar)

Napalmman.EXE (BN2, BN5 Team Protoman)

Flameman.EXE (BN3)

Burnman/Burnerman.EXE (BN4)

Blastman.EXE (BN6) Strong against Fire, weak against Elec
 *  Aqua/Water 

Abilities

No Slide: A water attributed Navi/virus will not slide on ice panels. (all games)

Moisture Freeze: If hit by an Aqua attack while on an ice panel, a Navi/virus will be frozen and the ice panel will turn back to a normal panel. (BN 6 only)

Styles

An Aqua attribute style will have the prefix "Aqua"

Souls

Aqua/Spoutsoul(Aqua/Spoutman) obtained in MMBN4 Blue Moon

Toadsoul(Toadman) obtained in MMBN5 Team Colonel

Crosses

Aqua/Spoutcross(Aqua/Spoutman) obtained in Falzar version

Bosses

Iceman.EXE (BN1)

Freezeman.EXE (BN2)

Toadman.EXE (BN2, BN5 Team Colonel)

Bubbleman.EXE (BN3)

Aqua/Spoutman.EXE (BN4, BN6)

Blizzardman.EXE (BN5)

Diveman.EXE (BN6) Strong against Aqua, weak against Wood.
 * Elec

Abilities

Conductor: when a Navi/virus is standing on an Ice panel, an Elec attack will do 2x damage regardless of the attribute of the Navi/virus.

Styles

An Elec style will have the prefix "Elec"

Souls

Thundersoul(Thunderman) obtained in MMBN4 Red Sun

Crosses

Eleccross(Elecman) obtained in Gregar version

Bosses

Elecman.EXE (BN1)

Magnetman.EXE (BN2, BN5 Team Protoman)