Responses to: how are you

Genki?

You good? (informal, only use to a close friend)

genki desu

I am great (a little informal...incorrect grammar )

hai, genki desu

I am great (formal)

mama desu

So-so... (a little informal)

Anata wa

and you? (formal)

ogenki desu ka?

how are you? (formal) [litterally translates to "are you well?"

Genki Jaarimasen

not well

Un, genki

yep! I'm good! (informal)