In verses 4...
Nor will he find, besides Allah, any protector (Waliyan) وَاللّهُ أَع'لَمُ بِأَع'دَائِكُم' وَكَفَى بِاللّهِ وَلِيًّا [Yusufali 4:45] But Allah hath full knowledge of your enemies: Allah is enough for a protector (Waliyan), But in verses 5:55 and 66:4, Allah says that He is Wali and along with Him, His messenger saww, true believers who establish prayers and pay Zakaat when they bow down (this refers to Imam Ali [as] who gave his ring to a beggar in state of bowing) are also the protectors/guardians.
and some believers are also our Waliys, does it mean that Allah is not the Only Wali (i.e. beside Him there are other Waliys too)? And does it mean that He is not enough as Wali? The simple answer to above question is, contrary to Salafi claim that whole Qur'an is Literal, there are figurative expressions in Qur'an, which must be interpreted accordingly.
Rule: When Allah says that He is the ONLY and SUFFICIENT Wali, then Rasool Allah [saww] and some believers are already included in it allegorically. (Allah has used the term Wali 43 times in the Qur'an in a sense that He is the only Guardian, or take no guardian beside him, and He is enough as Guardian and on four occasions, Allah has said that Rasool Allah [saww], some Momineen, Gabriel (as) and angels are also our guardians).
Salafi Tactics: You will find them ONLY quoting those verses in which Allah says that He is the Only and Sufficient Wali.