Synchronization

Full Synchro(nization) is a state where NetNavi and NetOp become one to improve focus and it puts the NetOp into direct contact with their NetNavi, transmitting effects on the NetNavi back to the NetOp. So, a high level of synchronization should complete the circuit enabling transmission of a NetOp's very will to their NetNavi, which greatly raises a NetNavi's fighting capabilities. Full Synchro fuses the mind of NetNavi and NetOp into one consciousness, getting rid of the delay between command and reaction, which can make a big difference between life and death during a battle.

Games
Full Synchro is first introduced in the final part of Mega Man Battle Network 3. When a NetOp entered the Cyberworld and fused with their NetNavi, they achieved Full Synchro, giving them a boost in their power and stats.

Full Synchro is available in the game mechanics of Mega Man Battle Network 4 onwards, displayed using the Emotion Window. Full Synchro is obtained when MegaMan performs a counter hit (hitting an enemy as they are executing an attack) using a non-dimming chip attack. In this state, the next chip attack has doubled strength, and enemies flash during the moment when they can be countered, encouraging the player to sustain Full Synchro. Full Synchro expires when the player performs a chip attack that is not a counter hit, or if MegaMan gets hit.

In Mega Man Battle Network 4, if the player performs enough battles without use of Dark Chips, MegaMan turns a slightly brighter shade of blue, and can randomly gain Full Synchro by being hit with non-dimming chip attacks, regardless of whether that hit was a counter hit or not.

From Mega Man Battle Network 5 onward, the player can no longer attain Full Synchro at random. Full Synchro also becomes available while the player is controlling other Navis. In the DS remake, using the Party Battle System, switching Navis while one is in Full Synchro may initiate a combination attack between the two Navis.

In Mega Man Battle Network 6, if MegaMan enters the "Tired" state from using up his Beast Out or "Very Tired" from using Beast Over, he cannot perform Full Synchro. Full Synchro still can be used while he is using a Beast Out, however.

Anime
Synchronization between NetNavi and NetOp is needed to perform Cross Fusion.

Manga
In the MegaMan NT Warrior manga, Full Synchro works much like how it is described, fuses the NetOp and NetNavi into one consciousness, but unlike other canons it differs drastically in one way: Whatever happens to the NetNavi in their world, happens to the NetOp in the real world (i.e. if a Navi gets slashed, their NetOp would receive a slash wound on the exact same spot). However, unlike game canon once a NetOp and NetNavi successfully do a Full Synchro, they can do it again at will as well as undo it at any time (usually when the battle is over or the battle is becoming too risky).

Perfect Synchro
Perfect Synchro has been thought of as the last state available in Full Synchro. It is ultimately Full Synchro at 100% (which removes all delay from the NetNavi's battle routine). However, this renders the NetOp's body in the real world to be soulless- in the state between life and death. Lan Hikari and MegaMan are the only NetOp and NetNavi duo known to achieve Perfect Synchro.