FlashMan steals a TetraCode for Alpha in Lan's school, and hypnotizes Lan's friends with Hypno Flash (a bright series of lights) when they interfere. Lan manages to escape and deflect the Hypno Rays with an umbrella he found in the school. MegaMan.EXE jacks into the school computer and defeats him. However, FlashMan self-destructs and leaves MegaMan with a glitch. It doesn't surface at first, but later he is unable to jack-out, forcing him walk back to his jack-in point. After defeating him, he can be encountered in ACDC area 3 at the pathway next to the teleporter that leads to the square. After that, he will be a random encounter in ACDC area 2.
He later reappears using Full Synchro with Rei in order to stop MegaMan in Castle Wily, but is defeated again. He then attempts to utilize his Shining Browser Crasher again on MegaMan, but ended up deleted by Tora and KingMan.EXE before completing it.
FlashMan first appears in the Net causing trouble for Nebula, fueled by Dark Chips. He goes in the Net and makes all the lights in DenTech City burn out. MegaMan tries to stop him, but he is too powerful and repels him. Roll tries to stop FlashMan herself, but fails and injures MegaMan accidentally. MegaMan needs to be repaired while FlashMan attacks again. Roll tries to stop him on her own once more, but is overwhelmed by him. MegaMan comes to rescue her and gains Roll Soul by working together with her. With it, he is able to drive FlashMan away.
He uses Dark Chips to make himself stronger and is sent to delete DesertMan.EXE for being captured. Before being deleted, DesertMan was being deteriorated by the Dark Chips and said the same thing would happen to FlashMan. After being defeated by a Cross FusedChaud, he returns to ShadeMan.EXE, and due to the Dark Chips side effects, becomes addicted to them and becoming just a shell of his former self and attacks ShadeMan, which results in his deletion. He is later revived by Dr. Regal, but is deleted again by MegaMan in Roll Soul.
He reappears as Asteroid FlashMan.EXE and is given to Rei Saiko by Slur. The duo then join Neo WWW under Tesla. In the end he and the asteroid version of DesertMan are deleted in Neo WWW's final fight with the Net Police, where he falls to CF-Lan, but, before he is deleted, gives one final goodbye to his operator.
Neon Light: FlashMan summons an orb of light that moves across the ground, randomly zigzagging as it travels forth. It does not travel past holes.
Flash Light: FlashMan summons two bulbs on the player's field. After some time, the bulbs will flash and disappear, causing paralysis. This attack pierces Invis, negating it, but cannot pierce Barriers, as it does no damage. The bulbs can be destroyed.
Spark Arm: FlashMan will move to the front of his area and hit in a widesword-esque fashion, also extending an extra panel forward. He often uses this with Area Steal and Flash Light.