4

4 or (4chan) is the child of Giovanni, as well as Aoooo's rival in Gen 4.5 (Randomized HeartGold).

History
During their first encounter in Cherrygrove City, 4 ran into Aoooo after stealing what was assumed to be a randomized Aipom from Professor Elm. Despite the Aipom using Attract first, Aoooo's Trapinch quickly ended the match with a swift Hammer Arm.

In Azalea Town, the Mob had troubles winning against 4, as his Pokémon had been randomized again to even stronger ones. He was also the cause of a dilemma, where the stream kept draining money after constantly losing battles against him. Without money, the Mob couldn't afford anything to catch Pokémon.

When challenged again in Goldenrod City, his team featured Ice Types, which further hampered the Mob's efforts.

4's Aipom became a Houndoom during the next rematches, then a Kricketune. The reason for this is that the ROM was randomized three times because of an in-game bug which would cause the Pokémon not to gain EXP from battles.

Name
He is often known as 4chan. This is derived from the website 4chan, and the suffix -chan. This suffix indicates affection, and is usually used for girls. Additionally, it has been used in the past to refer to characters in Twitch Plays Pokemon such as A and her Azumarill M4.

Personality/Lore
Perhaps the biggest part of 4's lore is his questionable gender. While some consider him male because he is canonically a boy, a growing part of the community considers 4 to be a female in disguise, primarily because when players were entering the name in-game, there was a point where only the symbol '♀' was input; however, this was deleted and eventually the rival's name became '4'.

4's personality does not differ much from the canon description of the HeartGold and SoulSilver rival. He (or she, according to the reverse trap theory) is Giovanni's son (or daughter) who went on a quest to become stronger than Team Rocket's former Boss, by defeating everyone in the way. 4 does not care about Pokémon at all, using them only as a means to achieve personal greatness.

4's behavior towards Aoooo is somewhat similar as the canon rival's one towards the player in the original games: he/she is ruthless, cold and looks down upon her. Apart from that, their interactions were never really put into consideration during the run, as the main focus was on defeating Bill and the incoming return to full glory of the Fossil Gods in Aoooo's party.

Trivia

 * 4 is the first rival to have a non-default name.
 * 4 was sometimes drawn in fanart using a scythe, a reference to the fact that the number 4 is linked with death in Japanese culture. Some even think that Aoooo's rival was the one that dealt the final blow to TPP's main antagonist, Bill, killing him with a swing of the weapon. However, the reasons for him/her doing this are not clear.