This is a fantastic topic and there is a lot to say.
The strongest leader in Animal Farm is undoubtedly Napoleon. We can see his strength as a leader in three ways. First, he ousts Snowball, who is clearly the more intelligent of the two. Second, he is able to rule the farm with an iron grip. No one can even question him. Third, he uses various means to rule. For example, when he needs muscle, he uses the dogs. When he needs a spokesperson, he uses Squealer.
Squealer is the spokesperson. He is master rhetorician. His use of language is eloquent and powerful. For example, when the pigs steal the apples and milk, Squealer is able to twist words and make an argument that sounds plausible. The pigs should have these things, and it is to the benefit of the farm! Here is the text:
‘Comrades!’ he cried. ‘You do not imagine, I hope, that we pigs are doing this in a spirit of selfishness and privilege? Many of us actually dislike milk and apples. I dislike them myself. Our sole object in taking these things is to preserve our health. Milk and apples (this has been proved by Science, comrades) contain substances absolutely necessary to the well-being of a pig. We pigs are brainworkers. The whole management and organisation of this farm depend on us. Day and night we are watching over your welfare. It is for your sake that we drink that milk and eat those apples. Do you know what would happen if we pigs failed in our duty? Jones would come back! Yes, Jones would come back! Surely, comrades,’ cried Squealer almost pleadingly, skipping from side to side and whisking his tail, ‘surely there is no one among you who wants to see Jones come back?’
Finally, Boxer is the ideal worker. He does not question the leadership and just works. And when things become harder, he works harder. The tragedy is that he works himself to sickness, and when he cannot work anymore, he is sold and turned into glue.