1. I like sheep. They can follow the shepherd well. They can't fight with other animals well.
2. I like parrots. They can imitate people's voices well. They can't clean houses.
3. I like giraffes. They can pick fruit on trees. They can't swim.
4. I like crocodiles. They can swim well. They can't fly.
(Would you check the short passages and correct errors in them, please?)
They're all grammatically correct.
I'd change the 3rd set a little bit, though:
... they can eat fruit off trees. ...