Due to the lack of time, I have only included some of the winners for each country, more winners' works at the provided links.
WORLD OPEN CHAMPION
THAILAND
TITLE : ANOTHER LATE NIGHT
BUILDER : VICHAYUTH EIAM-ONG
WORLD JUNIOR CHAMPION
INDONESIA
TITLE : BUILD FIGHTERS SEASON 3
BUILDER; CORNELIUS CAESAR WIDJAJA
AUSTRALIA
http://bandai-hobby.net/GBWC/australia/result.html
GBWC2015 Australia Open Category A 1st
TITLE : Go! Funnels!
MODELLER: Yukun Weng
GBWC2015 Australia Open Category A 2nd
TITLE: Water Melon Unicorn
MODELLER: Henry Hondros
CHINA
http://bandai-hobby.net/GBWC/china/result_final.html
CHINA
FINAL YOUTH COURSE
1 ST PLACE
GBWC2015 China Final Youth course 1st
The Devil King of The Sixth Heaven（征天魔王）
BUILDER: Nan Yang（南洋）
CHINA YOUTH COURSE , 2ND PLACE
GBWC2015 China Final Youth course 2nd
Spirit of Tears（泪的意志）
BUILDER: WANG CHANG BIN (王长斌)
HONG KONG
http://bandai-hobby.net/GBWC/hongkong/result.html
HONG KONG OPEN COURSE GROUP A , 1ST PLACE
GBWC2015 Hong kong 公開A組 1位
NIGHTINGALE (Long Distance Support Type)
（夜鶯（長距離支援型））
BUILDER: NG SIU WAI （伍少偉）
HONG KONG OPEN COURSE GROUP A , 2 ND PLACE
GBWC2015 Hong kong 公開A組 2位
HEAD HUNTER (MS-06K Series III) Liu Wang Chun Lawrence（廖宏俊）
ITALY
http://bandai-hobby.net/GBWC/italy/result.html
GBWC2015 Italy Open Category 1st
RX 93 Gesshoku - Lunar Eclipse
BUILDER : RICCARDO FORNI
GBWC2015 Italy Open Category 2nd
Across the sky
BUILDER :Omar Zampetti
JAPAN
http://bandai-hobby.net/GBWC/japan/index.html
TITLE : TALLGEESE (ARES) ~ THE GOD OF WAR
BUILDER ; ROKU TAKAOKU SEIYA 高奥誠也
JAPAN JUNIOR COURSE
TITLE : THE LAST SHOOTING
BILIDER ; HATA MAY 畑 めい)
INDONESIA
NO LINK PROVIDED
TITLE : FINAL BATTLE
MODLLER : RONNY HARTANTO
TITLE : BUILD FIGHTERS SEASON 3
MODELLER : CORNELIUS CAESAR WIDJAJA
MALAYSIA :
http://bandai-hobby.net/GBWC/malaysia/result.html
GBWC2015 Malaysia Junior A 1st place
happy dancing bears!
BUILDER : On Xin Jing
GBWC2015 Malaysia Junior A 2nd place
Lighting strike
BUILDER : Abigil Lim Xin Yi
NORTH AMERICA
http://bandai-hobby.net/GBWC/northamerica/result.html
GBWC2015 North America Open Category 1st
DASH'S LEGENDARY MOBILE SUIT U.N.O.M. TEST TYPE 001-MIXCOATL
KEVIN ZHANG
BWC2015 North America Open Category 2nd
MG JESTA HAVOC
BUILDER : HE NATE
PHILIPPINES
http://bandai-hobby.net/GBWC/philippines/result.html
GBWC2015 Philippines Junior A 1st place
NO TITLE
BUILDER : KEIANN MATTHEW G. PANGANIBAN
GBWC2015 Philippines Junior A 2nd place
NO TITLE
BUILDER : CHINOWLE J. FETALINO
SINGAPORE
bandai-hobby.net/GBWC/singapore/result.html
GBWC2015 Singapore Open A 1st
Burning Astray
BUILDER : Han Weihang
GBWC2015 Singapore Open A 2nd
Reload and Fight
BUILDER : Justin Yap Jia Hui
SOUTH KOREA
http://bandai-hobby.net/GBWC/southkorea/result.html
GBWC2015 South korea OPEN A 1st
RX - 78GP04G GERBERA
Kim Minho（김민호）
GBWC2015 South korea OPEN A 2nd
Deja Vu
BUILDER : Lee Jinho（이진호）
TAIWAN
http://bandai-hobby.net/GBWC/taiwan/result.html
GBWC2015 Taiwan Open A 1st
The Arrow of Justice (正義之箭)
BUILDER : Chou Yih-Ming（Dennis Chou）（周毅明）
GBWC2015 Taiwan Open A 2nd
Continue(傳承）
BUILDER : Lin Zih-Ciao（林子喬）
THAILAND
http://bandai-hobby.net/GBWC/thailand/result.html
GBWC2015 Thailand Junior A 1st
THE LAST WORK OF GUNTANK BUILDER : YANATHIP ANUPONGPHAN
GBWC2015 Thailand Junior A 2nd
G-GANG
BUILDER : ASHIRA NAEWBANTHAT