[quote=@Shadow Daedalus]

Martial Arts - defenceless without a gun and with an abhorrent detest for swords and other melee weapons, Nero learned to use his own body as a weapon out of necessity. Using a hybrid style incorporating techniques from across the 4 Blues, such as Fishman Karate, Rokushiki and Ryusoken, he can overpower most foes, but those specialising in Close-quarters with win most of the time against him. To give him an edge up, however, Nero can combine his gunplay and martial arts into a special series of 'Gun-kata' techniques.

[hider=Martial Arts]
A free-form style of fighting with moves borrowed from several major martial arts styles. (Moves are explained on respective One Piece Wiki pages, so I can't be bothered to re-write them all)
[i]Hyakumaigawara Seiken[/i] - Borrowed From Fishman Karate
[i]Karakusagawara Seiken[/i] - Borrowed From Fishman Karate
[i]Geppo, Tekkai, Soru, Kami-e[/i] - All Borrowed from Rokushiki
[i]Ryu no Kagizume[/i] - Borrowed from Ryusoken[/hider]

Let me know if anything needs adjusting

[/quote]

I'm leaving the rest of the character to the jurisdiction of Noodles, but I'm calling this part out. I'm wondering how he got to learn all these martial arts techniques from around the world WHILE ALSO being a sniper and a doctor. 

Not only does it eliminate his greatest weakness, which is being without weapons/in melee range, these skills are also way too advanced for an east blue character.  
Karakusagawara Seiken has only been done by Jinbe (literally the strongest fishman karate user in the series). The rokushiki techniques are extremely powerful, and he learned himself all the defensive ones (why would he need the offensive ones? He has guns and fishman karate. So he basically knows everything he'd ever need from rokushiki). 
Ryu no Kagizume has only been shown by sabo, who is the vice commander of the entire revolutionary army so obviously strong. And this technique took down a vice admiral in one shot.

I also want to point out the dream of my own character is to travel the world and learn various martial arts. Yet here comes a character who basically already knows all prominent martial arts displayed in the one piece world to a pretty good extend. This makes my own character basically moot. 

I'm really not sure why you need martial arts. You can be strong enough with just gunplay. Sorry if I'm sounding rude but I just can't agree with this being accepted.