My cat.

Today I will tell you about my cat.
My cat is called 'Pikachu'. Pikachu is a Pokemon name!
My cat is furry, but very, very nice. It have has a big and rounds eyes. Pikachu have has a lead pelage and it grated (I am not sure what you mean).
Pikachu is tall in comparation comparison to with other cats!
I love my cat.

Very good. It sounds like you have a lovely little cat. You just need to practice auxillary verbs (will, is)  and verb tenses (have, has, had).

Also, you can call your cat 'he' or 'she' instead of 'it'.