Mega Man Battle Network 5: Team ProtoMan^{[lower-alpha 2]} and Mega Man Battle Network 5: Team Colonel^{[lower-alpha 3]} are 2004 role-playing video games developed and published by Capcom for the Game Boy Advance (GBA) handheld game console. Combined, they make up the fifth mainline installment in the Mega Man Battle Network series, and follows Lan Hikari and his NetNavi MegaMan.EXE, as they attempt to take down Nebula, who have kidnapped Lan's father and taken over the internet, with an anti-Nebula task force.^[9]

Development on the game started during the localization of Battle Network 4, and alongside the development 4.5: Real Operation. It was announced in CoroCoro Comics in August 2004, with Team ProtoMan releasing in December 2004 in Japan; Team Colonel released three months later in February 2005, while both versions were released simultaneously for Western territories in June 2005. Battle Network 5 retains the same gameplay as its predecessor, but with the addition of "Liberation Missions" where the player must liberate squares with limited time to defeat the boss. The game also includes crossover content with the Boktai series by Konami.

Mega Man Battle Network 5 received a generally tepid reception from critics, with many finding it too similar to previous entries, and criticizing the aging presentation; in mid-2005, both versions were combined and re-released for the Nintendo DS as Mega Man Battle Network 5: Double Team DS^{[lower-alpha 4]}, which has updated sound and additional content not found in the GBA versions. The GBA versions were re-released as part of the Wii U Virtual Console in 2015, and are included in the Mega Man Battle Network Legacy Collection for PlayStation 4, Nintendo Switch and PC (via Steam), released in 2023. It was followed up by Mega Man Battle Network 6 in 2005, which acted as the finale of the series.

The gameplay of Mega Man Battle Network 5 is largely similar to that of its predecessors. The player explores the real world through Lan and the Net through MegaMan.EXE. When Lan plugs his PET, a handheld computer, into a computer with an interface jack, he can upload MegaMan.EXE to the cyber network, allowing him to explore and fight viruses as random encounters.^[9][10]

When MegaMan.EXE encounters viruses, the screen shifts to a battle screen set on a six by three square grid. On the left half of the grid is MegaMan.EXE, and on the other half are his opponents. MegaMan.EXE has a relatively weak arm cannon, the Mega Buster, but his main weapon is Lan's library of battle chips, one-use-per-battle special attacks which grant various abilities, including simple attacks, attack enhancements, defensive effects, terrain transmogrification, or assistance from other NetNavis. Before battle, the player can construct a folder consisted of thirty battle chips, and each turn of a battle (measured by a timer bar at the top of the screen), the player is presented with a random selection of these chips. The player can send MegaMan.EXE up to five battle chips, after which the battle takes place in real time, with MegaMan.EXE, controlled by the player, attacking with his Mega Buster, dodging attacks, or activating battle chips from his queue.^[9][10]

MegaMan.EXE joins a team led by either Lan's and MegaMan.EXE's rivals Chaud and ProtoMan.EXE or new characters Baryl and Colonel.EXE, and the members of this team assist MegaMan in various ways. MegaMan.EXE can take on the attributes of one of his teammates with a Soul Unison.^[9] The team plays its largest role in Liberation Missions, wherein MegaMan.EXE and the rest of his team enter a part of the Nebula-controlled Internet to free the area via a time-limited battle with a group of viruses.^[9][10][11] The Dark Chip system from the previous game was also reworked, with them now having to be obtained; it is also possible to use them to activate a "Chaos Unison", which resembles a normal Soul Unison with the main difference being that the Mega Buster is replaced with the effects of the Dark Chip he used for the Chaos Unison. While using this effect doesn't cause HP loss, it has to be done with careful timing, as charging with poor timing will end the Chaos Unison and cause an invincible, evil version of MegaMan.EXE to join the viruses and attack him for a short period of time using random battle chips.^[9][11]

Much like previous games in the series, Game Boy Advance copies of Mega Man Battle Network 5 can connect using the Game Boy Advance link cable to battle head-to-head or to trade battle chips.^[9] Battle Network 5 also includes content referencing the Boktai series by Konami,^[12] such as a crossover battle feature unlocked by combining both Battle Network 5 and Boktai 2: Solar Boy Django.^[10]

Protagonists Lan Hikari, MegaMan.EXE, and their friends are called to the SciLab headquarters at the request of Lan's father, Yuichiro Hikari. While at SciLab, mysterious agents invade, subduing everyone with sleeping gas, kidnapping Yuichiro, and stealing the friends' PETs and NetNavis. The agents turn out to work for Dr. Regal and his crime syndicate Nebula, which has returned after being defeated in Mega Man Battle Network 4. Nebula subsequently takes over the Net with an army of viruses and Darkloids: powerful Navis that use DarkChips.^[9]

While investigating another disturbance at SciLab, Lan meets either Chaud (in Team ProtoMan) or newcomer Baryl (in Team Colonel), who recruit him to begin forming an elite team of NetNavis to liberate the Net from Nebula's control. In a series of almost identical scenarios between games, Lan meets other powerful NetNavi operators and recruits them. Through the team's efforts, the Net is liberated and peace is restored. However, the occupation of the Net is revealed to be a diversion by Nebula while searching for "The Hikari Report," a research project by Lan's late grandfather, Dr. Tadashi Hikari.

The Hikari Report is explained as a research project by Dr. Hikari and Dr. Wily to create SoulNet, a network connecting the minds and souls of humans and NetNavis across the world. The two believed that SoulNet could bring peace and unity to the world, but were unable to finish their research. Upon obtaining the report and completing SoulNet, Regal intends to unleash Nebula Grey, a program of pure hatred and darkness, upon it, corrupting all humans and NetNavis in the world. Lan and MegaMan also discover that Regal is Dr. Wily's son.

The liberation team storms Nebula's base and confronts Regal in the SoulNet server room. After defeating Nebula Grey, MegaMan seals it and the room begins to self-destruct. While the heroes evacuate, Yuichiro stays behind to speak to Regal about their fathers' research while a mysterious voice causes the SoulServer to overload. In Team ProtoMan the speaker is unseen, while in Team Colonel it is revealed to be Dr. Wily, who also commands Baryl to rescue Regal and Yuichiro. Because of the SoulServer overload, Regal has many of his memories erased and is now a peaceful scientist. With their NetNavis back, Lan and MegaMan's friends join them on the Net.

Development of the game started during the localization of Mega Man Battle Network 4, and during the development of Rockman.EXE 4.5: Real Operation (2004). The developers described this period at Capcom as a difficult time.^[13][14] The game was first advertised in the Japanese magazine CoroCoro Comics in August 2004.^[15]

Team ProtoMan released in Japan on December 9, 2004,^[1] while Team Colonel released three months later on February 24, 2005;^[1][2] the reason for this delay is unknown, since both games were finalized at roughly the same time.^[16] Viewers of the anime film Rockman.EXE the Movie: Program of Light and Darkness would also receive a special copy of Team Colonel with an e-Reader card for the transformation "BassCross MegaMan".^[2] Both versions of Battle Network 5 were released simultaneously on June 10, 2005, in Europe,^[3] and June 21, 2005, in North America.

The Game Boy Advance versions were re-released onto the Wii U Virtual Console in Japan on September 9, 2015,^[17] and in North America on December 12, 2015.^[18] The games are also included in the Mega Man Battle Network Legacy Collection for PlayStation 4, Nintendo Switch and PC via Steam, released in 2023.^[19][20]