Formal:
* Olá a todos. (This is the most common and formal way to greet everyone)
* Bom dia a todos. (Good morning everyone)
* Boa tarde a todos. (Good afternoon everyone)
* Boa noite a todos. (Good evening everyone)
Informal:
* Oi gente! (This is a very casual and friendly way to greet everyone)
* E aí, galera! (This is a more informal and slang way to greet everyone, similar to "Hey guys!" in English)
* Fala galera! (This is a more colloquial way to say "Hey everyone!")
Other options:
* Olá, pessoal! (Hello, people! This is a bit more formal than "Oi gente!")
* Salve, galera! (This is a more informal and slang way to say "Hey everyone!")
It's important to choose the right greeting depending on the situation and your relationship with the people you are addressing.