By definition, “poor behaviour” includes a very broad spectrum of behaviours. It ranges from things that disrupt the team (e.g., not sharing information, being late, missing deadlines, long lunch breaks), through things that derail the team (e.g., forming cliques, gossip, being dishonest, excluding someone from the team) to things that lead to the individual being excluded by their workmates (e.g., small personal space, poor personal hygiene).

The way to handle conversations across this behaviour spectrum is very similar.  If there is a poor behaviour you need to address it quickly, preferably as it happens before it impacts the rest of the team.

Consider these questions: