What is the Biblical basis for Jesus Christ being a created being according to Jehovah’s Witnesses? Jehovah’s Witnesses believe that Jesus Christ is a created being. What is the Biblical basis for this position?
Taking a look  at this Watchtower article scriptural citations appear to be from The Common Bible. I believe this is a 1973 edition of the revised standard version. 

The apostle Paul wrote concerning Jesus Christ: 


  He is the image of the invisible God, the first-born of all creation; for in him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or principalities or authorities—all things were created through him and for him. He is before all things, and in him all things hold together.”—Col. 1:15-17


Looking at Paul’s further words helps explain what is meant by the phrase firstborn of all creation: 


  He is the head of the body, the church; he is the beginning, the first-born from the dead, that in everything he might be pre-eminent.”—Col. 1:18


The Greek words for both “first-born” (protótokos) and “beginning” (arkhé) show Jesus as the first one of a group or class, “the body, the church,” meaning that  he has preeminence in this respect. 
Jesus also has preeminence in another class as the firstborn of the dead. This means Jesus is the first one resurrected to endless life from among all the human dead.—1 Cor. 15:22, 23.

These same Greek words are found in the Greek Septuagint translation at Genesis 49:3: 


  Ruben, thou art my first-born [protótokos], thou my strength, and the first [arkhé, “beginning”] of my children.” 


We believe that biblical statements like these make it reasonable to conclude that the Son of God is the firstborn of all creation in the sense of being the first of God’s creatures. Jesus in fact refers to himself as “the beginning [arkhé] of God’s creation.” (Rev. 3:14,). 

Most professed Christians object to the idea of Jesus as being a created person. They believe that Jesus is himself Almighty God, the second person of a “trinity” of three coequal, coeternal persons in one “godhead.”

Trinitarians protest that  the Greek expression (at Revelation 3:14) for “the beginning of God’s creation” means “the origin (or ‘primary source’) of the creation of God.” 
One Greek scholar,Henry Alford, takes this viewpoint as correct. However he concedes in his work “The Greek Testament”: “The mere word arkhé would admit the meaning that Christ is the first created being”. Thus he notes that this is why Arians taught that Colossians 1:15 is in effect saying [“the first and most excellent of all God’s works”]

The book The Expositors Greek Testament says: “to understand Revelation 3:14 as meaning that Jesus is “the active source” of creation, rather than the first created person, one must interpret arkhé “as in Greek philosophy and [non-Biblical] Jewish wisdom-literature,=aitía or origin.” 

But it is clear that bible writers did not follow Greek philosophy.

Some would argue,  if Jesus is a created being explain the phraseology “in him all things were created”.

On occasion the Bible uses “all” in a way that allows for exceptions. For example, we read at 1 Corinthians 15:27:


  But when it says, ‘All things are put in subjection under him [Jesus Christ],’ it is plain that he [God] is excepted who put all things under him.” 


Also consider that the Bible states that “through one man,” Adam, “death spread to all men.” (Rom. 5:12) 
Was Adam  part of the “all men” to whom death “spread”?   No. Because previous to Adam there was no human who could have spread death to him. Adam was nonetheless a man. 

In this way we can reason that although Jesus was not part of the “all things” that came into existence through him, he was, nevertheless, a created person, the very first creature of God. 

Since  Jehovah’s witnesses are convinced that Jesus  is a created person, we understand that he cannot be Almighty God. 

This is why we point repeatedly to verses that portray him as in a position subordinate to God. 
For example, the apostle Paul said about the resurrected Jesus : 


  I want you to understand that the head of every man is Christ, the head of a woman is her husband, and the head of Christ is God.” (1 Cor. 11:3) 


And notice the words of Jesus to John in Revelation 3:12 Jesus said concerning himself


  He who conquers, I will make him a pillar in the temple of my God; never shall he go out of it, and I will write on him the name of my God, and the name of the city of my God, the new Jerusalem which comes down from my God out of heaven, and my own new name.


Four times in this verse alone Jesus refers to his Father, Jehovah, as “my God”.

We do not teach that Jesus did not exist before he became a human born of Mary.  Nor do we teach that Jesus is just another angel. 

We recognize the exalted position that Jesus occupies next to God. Before ascending to heaven, Jesus said to his disciplesjust before ascending to heaven


  All authority in heaven and on earth has been given to me.” (Matt. 28:18)


It was appropriate for Jehovah to ‘give’ to his Son such authority, since Jesus is the firstborn (preeminent) of all creatures. 
Right in line with this exalted preeminent position granted to Jesus the apostle Paul wrote concerning him:


  [God] raised him from the dead and made him sit at his right hand in the heavenly places, far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in that which is to come; and he has put all things under his feet and has made him the head over all things for the church.”—Eph. 1:20-23


For more info on the name that is above all names see this answer to a related question.