From Bulbapedia, the community-driven Pokémon encyclopedia.
A round is the Pokémon Adventures equivalent of the Pokémon anime's episode. Rounds divide the chapters and volumes into sections, which have a separate plot, or continue the events of the last round. In the Japanese magazine serialisation each round is given a subtitle that reflects the round's events. In the tankōbon releases each round is named after a Pokémon encountered in that certain round, such as VS. Pokémon. The rounds of the fifth chapter don't have titles following this convention and are only known by their subtitles in the Japanese releases. In the English translations, the rounds are titled after puns or the same as the Japanese title. Unlike in the Chuang Yi releases, the rounds of the fifth chapter are named in the VIZ Media version. Rounds are also added up into volumes; there are times when two rounds in the serialization are combined into one in the volume release. The number of rounds in a chapter or a volume is not definite. The length of a round is also not specified.
In the Chuang Yi's translations, rounds are referred to as "chapters"; in the VIZ Media's translations, they are mostly referred to as "adventures", although "chapter" has also been used.