Patch Cards in Mega Man Battle Network 5
From The Rockman EXE Zone Wiki
Using the e-Reader+, both versions of Rockman EXE 5 can scan e-Reader cards to further customize their MegaMan, as well as other features.
Information
e-Reader Cards (Known in game as Mod Cards) can be used to enhance your MegaMan with Abilities not possible normally. Unlike how Mod Cards worked in the EXE 4, with slots for cards, EXE 5 and 6 Introduced an MB system. Each card now has a certain MB value, with MegaMan having a limit of 80 MB. Cards with higher MB generally have better Ability, and previous cards must be deleted when scanning new mod cards. Individual cards can be turned on or off when needed, but this does not lower the MB limit.
Mod Card Types
e-Reader Cards come in 3 types; Mod Cards, Item Cards, and Rare Chip Distribution (Applies to two cards only). Item Cards give things such as chips, money, bugfrags, or subchips and can only be used once per file. This is also the only method on GBA to obtain Leaders Raid and Chaos Lord (This was given lotto codes in the DS version).