How bout Isaac?
I think Luke would be pretty solid from being turned into a nickname. Like others have said people will find a way to get a nickname out of it though. Lukey maybe or Little Lukey Wonderpants? Who knows with kids these days.
Lefty and Red are family names although it’s been awhile since those have been used. My great-grandfather was Lefty and his last name was Love so he was Lefty Love. I’ve always thought that it sounded cool. Red was a grand-uncle.
Lou. Lulu. Or Looney. Or Looneybird. They only get meaner from there.
(I’m telling you, it can’t be done. There is no nickname proof name!)
My son is David Paul. I call him Paul, the school calls him David, lots of people call him DavidPaul. He answers to all of them. Paul is a good common name, but not too overused.
Anyway, off your list, I like John Paul.
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Tahssa**, the obvious nickname for Luke is “Puke”. 
My cousin is named Hailey. Everyone calls her “Hay” or sometimes, “Hay-Hay”. She’s going to have a rough time of it. She’s only two now, but whenever we’re out in public and someone nearby says, “Hey!” her head whips around to find out who’s talking to her.
Tahssa, I have a nephew named Luke. People call him “Lukey”. His other nickname is “The Lukinator”, and God only knows where that came from.
My full name is Melissa. I despise the name Missy, which is what everyone wanted to call me when I was a child. I managed to put a stop to that, and everyone switched over to “Lissa”. I only ever heard “Melissa” if I was in trouble, and to this day, I only use my full name if I’m signing an official document.
Or Skywalker. 
(I actually did meet a set of twins named Luke and Leia a few years ago. Ugh.)
Well there you go blinkingblinking Lissa just found the perfect name. “The Lukinator”. Then you could call him “Luke” as a nickname and it will still be normal.
Of course being called “The Pukinator” would just be an added bonus for when he’s a baby and puking all the time. Even when he’s in school I think “The Pukinator” would be considered cool by the kids.
How did *that *happen, Mel?
Knew an Isaac in high school. Everyone called him Sicko.
When I was a kid, everyone called me Sally. I don’t hate it, but it’s just not me. I’m glad, because by the time I was in school, I was back to “Sarah,” and after that only elderly relatives stuck with Sally. Does anyone use Sally as a nickname for Sarah anymore?
Anyway…back to the OP…I like John-Paul a lot, but my main problem with it is that, to me, it conjours up images of 1) The Beatles and 2) Pope JPII. Now, I am a fan of both, don’t get me wrong, but for me, the association might be TOO strong. Don’t know if it would be the same in Australia, though.
I strongly agree with earlier posters that it’s best to give children formal names officially, and call them by whatever nickname you want. Robert is a great name, and you can call him Robbie, and then he can be Rob when he gets older.
I just got done reading “Freakonomics” and there is a chaper on baby names. He suggests that popular names start out as names wealthy people use, then trickle down from there. When they reach the middle class and then lower class you start seeing them everywhere, and everyone is like “where did this name come from?” But apparently the super upper class are the ones to popularize names (not celebrities as one might think, they tend to follow trends rather than cause them). Based on past patterns he has made predictions about what the most popular baby names in 2015 are going to be, and already some of them are coming up! So apparently there is some kind of reason to it all. I think Atticus and Harper were both on that list, IIRC, as well as Asher plus some I have never even heard before.
It’s an interesting read, he also gives lists of names divided by class and race. Apparently I gave my son a very white name. A different take on the baby name topic.
From Luke it is a short hop to Lucas Mucus.
How about Alexander. Can’t imagine any short forms from that! 
I was a remarkably stubborn child. I announced to all and sundry that my name was not Missy and I would henceforth refuse to answer to it. I stuck to my guns, even though I have a clear memory that it cost me a long time-out in preschool. (My mom came in and talked to my teacher who agreed to stop calling me Missy.)
“Missy” just ain’t* dignified.*
My mother many years ago had a 3rd grade student whose full legal name was Teddy Jack. As a result, she impressed upon me the stupidity of giving kids nicknames as legal names.
And obviously I’m looking at your list with a different-hemisphere bias because almost none of those names either appeal to me or sound nickname-proof.
I knew I guy named Rick once, and it turned out his real name was Ricky Joe. He was trying very hard to hide that from people!
Come to think of it, our landlord’s legal first name is Ricky. It’s not surprise he goes by his middle name, Shawn.
You know, that really pisses me off. It’s not your name, why would the teacher use a term that’s not your name and have to be told by mom not to? Had your mom introduced you as Missy?
Grrr.
“Hi, I’m Gwendolen.”
“Hi, Gwen, nice to meet you.”
Did I SAY “Gwen”? No, I don’t think that I did.*
Anyhoo, for the love of God do not name your son Darcy. Luke, Adam, Leo, Paul, these are all nice. Darcy? Hells no.
*FTR, I usually introduce myself as Gwen and I certainly answer to it. But at least use the name I used first.
Rozzer. I need to find someone called Roy now and call him that!
I LOVE our ability to create a nickname out of anything. My colleages call me “Chez” as a shortening of my name. Now my clients are calling me it. It cracks me up!
Paris.
No, the Trojan warrior, Paris. Great hero.
Brian. Means “Strong.”
Aaron.
Horatio. Another hero.
Tris (a signature. Not a suggestion.)
Trying to find a name that won’t lend itself to nicknames for an Australian child is an exercise in futility. Supposing for just one moment that you do manage to find a name that absolutely cannot be nicknamed in any way, shape or form by anyone, ever, they’ll just switch to calling him by some variant of his surname. Guaranteed. Pretending you’ve called your son Ray Smith and Ray is bulletproof against nicknames (pretend with me people, please), you know they’re going to call him Smitty or Smitto or Smitter or Chunks (ever since that amusing night with the 4 slabs of beer and the pie eating contest) or Bluey or Slim or Wonky.
I dislike nicknames as legal names. I’m from the school of thought that says that it’s good to have a nickname for family and friends to call you by and a sensible legal name that you can tell the judge without raising any eyebrows (my mother is from the opposing school of thought, and thinks you should just have one name for all occasions, and if it’s short and easy to spell, so much the better). My cousin named her daughter Evangeline and nicknamed her Evie - my mother hates Evangeline and keeps complaining they should have just called her Evie and been done with it, while I am glad that the child has a longer, more dignified name to grow into when she’s an adult.
Finally, as a Carol who is not a Caroline, I have to tell you that your Robbie or Charlie will spend their life correcting people who want to lengthen their name. Some people just can’t call you by the name you introduce yourself by, and just as a formal name will run into people who want to nickname it, a shorter form will constantly come up against people who want to lengthen it. Robbie will spend the rest of his life telling people “No, it’s not Robert, it’s just Robbie”, while Robert will want to hand out cards that say “It’s Robert, not Robbie”. You can’t win - so choose a name on it’s other merits, because people are going to bastardize it no matter what.
I’m sure I’ve mentioned this before, but my MIL gave her second son a name that she and her husband were certain it couldn’t be shortened: Troy. Despited this, the other brothers (including my husband) still found a way to shorten it, and still refer to him as Roy. All the immediate members of my husband’s family have names that have been shortened or made into nicknames.
On the flip side, my immediate family have never opted to shorten or alter any of our names. My parents have always been known as their full names, and it’s only people who don’t know them well at all who refer to them as Pete and Sandy!