Questions & Answers about Kaikki tulivat paitsi minä.
Here kaikki means everyone / all the people.
Finnish kaikki can also mean everything, so context matters:
- Kaikki tulivat. = Everyone came.
- Kaikki meni hyvin. = Everything went well.
In your sentence, because the verb is about people coming, kaikki is understood as everyone.
Finnish does not follow English here.
When kaikki means all the people / everyone, Finnish normally uses a plural verb:
- Kaikki tulivat. = Everyone came.
When kaikki means everything, singular is common:
- Kaikki on valmista. = Everything is ready.
So tulivat is plural because kaikki refers to a group of people.