In your example:-

The word “some” at the start of a sentence must have a capital “S”.

The word “the” must be replaced by “that” or “which”.

The subject of the sentence, the word “qualities” is plural, so the verb “is” which is singular must be changed to “are” which is also plural.

You are trying to describe qualities. For that you need to use nouns. The word “gentle” is an adjective. This must be changed to the noun “gentleness”.

The order in which you present the qualities listed is not really important, but it reads slightly better when like qualities are together.

I hope this is clear.

some qualities making an animal a best friend are; loyalty, companionship, obedience and gentleness.

so it will be :

some qualities THAT make an animal a best friend is loyalty, companionship, obedience and gentle.