Formal:
* Hola a todos: This is the most common and neutral way to say "hello everyone."
* Buenos días a todos: This is used in the morning.
* Buenas tardes a todos: This is used in the afternoon.
* Buenas noches a todos: This is used at night.
Informal:
* Hola a todos: This is also a common way to say "hello everyone" in informal settings.
* ¡Hola a todos!: The exclamation mark adds a friendly tone.
More specific:
* Hola, gente: This literally translates to "hello, people" and is a more casual greeting.
* Saludos a todos: This means "greetings to everyone."
* Un saludo a todos: This means "a greeting to everyone."
The best translation will depend on the specific situation. For example, if you are speaking to a group of people you don't know very well, it would be more appropriate to use a formal greeting. However, if you are speaking to friends or family, you can use a more informal greeting.