The view of Ahl al-Sunnah towards the Sahaabah and the leadership of Abu Bakr al-Siddeeq
Question

what evidence do you have that tells you Imama Ali(A.S.) isnt suppose to be  the leader after th Prophet muhammed(A.S).
Praise be to Allah.One of the basic principles of Ahl al-Sunnah wa’l-Jamaa’ah is that they have nothing against the Companions of the Messenger of Allah (peace and blessings of Allah be upon him) and they do not say anything against them. Their hearts are free of any hatred, resentment and rancour (towards them) and they do not say anything (about them) that is not appropriate or befitting, because Allah says (interpretation of the meaning): 
“And those who came after them say: ‘Our Lord! Forgive us and our brethren who have preceded us in Faith, and put not in our hearts any hatred against those who have believed. Our Lord! You are indeed full of kindness, Most Merciful’”[Al-Hashr :10]
And they obey the Prophet (peace and blessings of Allah be upon him) who said: “Do not revile my companions, for by the One in Whose hand is my soul, if one of you were to spend in charity gold equal to the size of Mount Uhud, he would not achieve the status of one of them, or even come halfway.” (narrated by al-Bukhari, 3637; Muslim, 2541).
One of the basic principles of Ahl al-Sunnah is that they accept that which has been narrated in the Qur’aan and Sunnah, and the consensus of the scholars, concerning the virtues and status (of the Sahaabah). They give precedence to those who spent and fought before the victory – the treaty of al-Hudaybiyah – over those who spent and fought afterwards, because Allah says (interpretation of the meaning): 
“Not equal among you are those who spent and fought before the Victory. Such are higher in degree than those who spent and fought afterwards. But to all Allah has promised the best (reward). And Allah is All-Aware of what you do” [Al-Hadeed 57:10]
They give precedence to the Muhaajireen over the Ansaar, because Allah says (interpretation of the meaning):
“And the foremost to embrace Islam of the Muhaajiroon and the Ansaar and also those who followed them exactly (in Faith). Allah is well-pleased with them as they are well-pleased with Him. He has prepared for them Gardens under which rivers flow (Paradise), to dwell therein forever. That is the supreme success”
[Al-Tawbah 9:100.] So the aayah gives precedence to the Muhaajireen over the Ansaar.
They believe that Allah said concerning the people of Badr – who numbered three hundred and umpteen – “Do whatever you like, for I have forgiven you,” because the Prophet (peace and blessings of Allah be upon him) said, “Maybe Allah looked at the people of Badr and said, ‘Do whatever you like, for I have forgiven you.’” (Narrated by al-Bukhari, 3007; Muslim, 2494 - from the hadith of ‘Ali ibn Abi Taalib) 
They believe that no-one who gave the oath of allegiance (bay’ah) under the tree will enter Hell, as the Prophet (peace and blessings of Allah be upon him) said. Rather Allah is pleased with them and they are pleased with Him, and they numbered more than one thousand and four hundred. Allah says (interpretation of the meaning): 
“Indeed, Allah was pleased with the believers when they gave the Bay‘ah (pledge) to you (O Muhammad) under the tree, He knew what was in their hearts, and He sent down As-Sakeenah (calmness and tranquillity) upon them, and He rewarded them with a near victory”[Al-Fath 48:18]
And the Prophet (peace and blessings of Allah be upon him) said: “In sha Allah, no one among the companions of the tree, those who gave their oath of allegiance beneath the tree, will enter Hell.” (Narrated by Muslim, 2496). Among those who pledged allegiance beneath the tree were Abu Bakr, ‘Umar, ‘Uthmaan and ‘Ali, may Allah be pleased with them all. 
And they (Ahl al-Sunnah) bear witness that those will enter Paradise who the Messenger of Allah bore witness that they would enter, such as the ten (who were given the glad tidings of Paradise), and Thaabit ibn Qays ibn Shammaas, and others among the Sahaabah (may Allah be pleased with them). The Prophet (peace and blessings of Allah be upon him) said: “Abu Bakr will be in Paradise, ‘Umar will be in Paradise, ‘Uthmaan will be in Paradise, ‘Ali will be in Paradise, Talhah will be in Paradise, al-Zubayr will be in Paradise, ‘Abd al-Rahmaan ibn ‘Awf will be in Paradise, Sa’d will be in Paradise, Sa’eed will be in Paradise and Abu ‘Ubaydah ibn al-Jarraah will be in Paradise.” (Narrated by Abu Dawood, 4649; al-Tirmidhi, 3747; classed as saheeh by al-Albani). 
They affirm that which has been narrated in mutawaatir reports from ‘Ali ibn Abi Taalib (may Allah be pleased with him) and others, that the best among this ummah after its Prophet is Abu Bakr, then ‘Umar. It was narrated that Muhammad ibn al-Hanafiyyah said: “I said to my father (‘Ali ibn Abi Taalib), ‘Which of the people is the best after the Messenger of Allah (peace and blessings of Allah be upon him)?’ He said, ‘Abu Bakr.’ I asked, ‘Then who?’ He said, ‘ ‘Umar.’ I was worried that he would say ‘Uthmaan, so I said, ‘Then is it you?’ He said, ‘I am just a man among the Muslims.’” (Narrated by al-Bukhari, 3671). So they (Ahl al-Sunnah) list ‘Uthmaan as the third and ‘Ali as the fourth, may Allah be pleased with them. 
See al-Waasitiyyah by Shaykh al-Islam Ibn Taymiyah, with commentary. 
Secondly: it is part of the belief of Ahl al-Sunnah that the most deserving of the people to succeed the Messenger of Allah (peace and blessings of Allah be upon him) was Abu Bakr al-Siddeeq (may Allah be pleased with him). The evidence for the leadership of Abu Bakr (may Allah be pleased with him) is as follows: 
1 – It was narrated from Muhammad ibn Jubayr ibn Mut’im that his father said: “A woman came to the Prophet (peace and blessings of Allah be upon him) and he told her to come back later. She said, ‘What if I come back and do not find you?’ as if she was referring to death. He (peace and blessings of Allah be upon him) said, ‘If you do not find me, then go to Abu Bakr.’” (Narrated by al-Bukhari, 3659). 
2 – It was narrated that Ibn Mas’ood said: “The Messenger of Allah (peace and blessings of Allah be upon him) said: ‘Take as your leaders those who come after me, Abu Bakr and ‘Umar.’” (Narrated by al-Tirmidhi, 3805; classed as saheeh by al-Albani). 
3 – It was narrated that Ibn ‘Umar (may Allah be pleased with them both) said: “The Messenger of Allah (peace and blessings of Allah be upon him) said: ‘Whilst I was standing by a well, drawing water from it, Abu Bakr and ‘Umar came. Abu Bakr took the bucket and drew one or two buckets, but there was some weakness in his drawing. May Allah forgive him. Then ‘Umar bin Al-Khattaab came and the bucket turned into a very large one in his hands. I had never seen such a mighty person as he in doing such hard work till all the people drank to their satisfaction and watered their camels that knelt down there.’” (Narrated by al-Bukhari, 3676).  
Ibn Hajar said in his commentary on this hadith: 
“Whilst I was standing by a well” means, in a dream. “Drawing water from it” means, filling a bucket with water. “He drew one or two buckets (dhanooban aw dhanoobayn)”: dhanoob refers to a large bucket when it is full of water. It seems to me that this refers to the major conquests which took place during his reign (as khaleefah), which numbered three. Hence the hadith does not refer to the number of buckets in the case of ‘Umar, rather it describes his drawing of water as ‘mighty’, referring to the many conquests that would occur during his reign as khaleefah. And Allah knows best. 
Al-Shaafa’i mentioned the interpretation of this hadith in al-Umm, where after quoting it he said: The meaning of the phrase “but there was some weakness in his drawing” is that his time of leadership was short, because of his untimely death and the fact that the war against the apostates (ahl al-riddah) kept him from reaching the level of conquests attained by ‘Umar during his lengthy reign as khaleefah. 
With regard to the phrase “May Allah forgive him,” al-Nawawi said: This is a du’aa’ on the part of the one who is speaking, i.e., there can be no other interpretation. Others said that it was an indication that the death of Abu Bakr was close. A similar case is to be seen in the aayah in which Allah says to His Prophet (peace and blessings of Allah be upon him): 
“So glorify the Praises of your Lord, and ask His forgiveness. Verily, He is the One Who accepts the repentance and Who forgives”[Al-Nasr 110:3 – interpretation of the meaning]
This aayah was an indication that the death of the Prophet (peace and blessings of Allah be upon him) was close. I say: it may be that it was an indication that the small number of conquests during his time was not his fault, because the reason for that was the brevity of his rule, and the meaning of forgiveness is to remove any blame from him. 
“And the bucket turned into a very large one in his hands” means, it became a huge bucket. “I had never seen such a mighty person as he” means that he achieved the ultimate. 
4 – It was narrated that ‘Aa’ishah said: “The Messenger of Allah (peace and blessings of Allah be upon him) said to me when he was sick, ‘Call Abu Bakr for me, your father and your brother, so that I may dictate a letter. For I am worried lest someone who is ambitious says that he is more entitled to the position of leadership, but Allah and the believers will not accept anyone other than Abu Bakr.’” (Narrated by Muslim, 2387). 
5 – During his final illness, the Prophet (peace and blessings of Allah be upon him) appointed Abu Bakr al-Siddeeq to lead the Muslims in prayer and he did not accept anyone else to take his place. The fact that he was appointed to take his place in the case of minor leadership (leading the prayers) indicates that he would succeed him in the case of major leadership (as imam or khaleefah). 
And Allah knows best.