Saya with kamu.
My understanding is that Saya is formal and Aku is informal for the first person (I, me, mine). Anda is the formal and Kamu is the informal for the second person (you, your). But most of the sentences here use Saya with/and Kamu. Would you really talk that way? Referring to yourself formally and someone else informally? I would think that when using Saya you'd use it with Anda and Aku with Kamu.
The most common way to address someone in Indonesian is using an honorific and a name. Most commonly used honorifics are pak, bu, mbak, mas (or their equivalents in other ethnic languages). For example, someone might ask me:
"Apakah Mbak Femmy suka menggunakan Duolingo?" "Do you (Mbak Femmy) like using Duolingo?"
When you translate the sentence into English word per word, it sounds like you're speaking in third person, very awkward. But in Indonesian, we don't feel like it's in third person. It feels very natural.
Personally, I rarely use the word "kamu" or "kau" or "Anda" in conversations. With friends of the same age or younger, I'll drop the honorifics and use their names. Only with my bestfriends, I use "lu" (and refer to myself as "gue"), which are very informal pronouns used mainly in Jakarta and Bandung.
Now this is just my personal usage, and other people do use "kamu" or "kau" in informal conversations.
People from different ethnic groups also use pronouns differently. For example, Batak people use "kau". Some Javanese people use "sampeyan". Some people in Islamic circles use "antum".
Just about everyone uses "saya", it's even common in informal settings. I can't give statistic, but it's used almost as often as "aku" in informal speech. But almost no one uses "anda" outside of formal speech, so you'd hear "kamu" a lot.
Also, despite the formality of "anda" using it outside formal speech feels like you're implying the one you're speaking to are a stranger.
Hi, You are right - saya is more formal than Aku. You only use Aku with someone who you are familiar with. Kamu is not very polite. Anda is preferred. You don't ever call someone older than you kamu. Then you have Saudara which is like 3rd person If you dont know someone and use kamu it's not polite. So, using Saya and kamu is ok if you know someone, but if you do not know someone you do not call them kamu. If they are older than you or are more senior than you, you do not use kamu.
I remember translating an English novel that is set in 19th-century England, which featured a very formal society. I use "saya/Anda" for conversations between high-born people, "saya/kamu" between high-born husband and wife. When a high-born speaks to a servant, I use "saya/kamu", and when a servant speaks to his master, I use "saya/Tuan". For conversations between commoners, I use "aku/kau".