A: He hasd a dog for two years already.

He thinks it was a good choice for them, because they have a big house with a garden, so the dog has a lot of splace forto playing.

AThey all have different characterpersonalities.

One loves sleep, another to play, but all of them loves people.

C: This person has an aquarium with two fishes.

He likes to give them food and watches them swim.

D: This person haves a parrot.

But a few weeks ago it stopped eating and talking.

They went to the vet and he prescribed some medicine, so the parrot is goodwell now and talks again.

But the person talksays that he has a dog and he mustn't to buy a new pet every time.

So he buys a new toy for his dog there.

So they went to the city shelter and tookgot a dog from there.

A: He hasd a dog for two years already.

He thinks it was a good choice for them, because they have a big house with a garden, so the dog has a lot of placeroom for playing.

All have different characterpersonalities.

One loves to sleep, another loves to play, but all of them loves people.

We use "love" for "all of them" because "all of them" is similar to "they". We say "they love" instead of "they loves".

C: This person has an aquarium with two fishes.

He had one for 6 months, then bought the another one.

"the other one" sounds like you are talking about a specific aquarium. Since you didn't talk about the other aquarium before, we can say "another one" to be more general.

D: This person haves a parrot.

It's named is Polly.

It's named Polly is ok, but it's more common to say "It's name is Polly".

But a few weeks ago, it stopped eating and talking.

But the person talksays that he has a dog and he mustn't to buy a new pet every time.

So he buyought a new toy for his dog there.

You can also say "buys" if he buys toys regularly.

It's named is Chester.

It's named Chester is ok, but it's more common to say "It's name is Chester".

A: He's hasd a dog for two years already.

He thinks it was a good choice for them, because they have a big house with a garden, so the dog has a lot of place for playingThe dog has a lot of place for playing since they have a big house with a garden.

If we write something like, "He thinks it was a good choice for them," then we expect the good choice was for the person and not the dog. A sentence with this phrase would be something more like this: "He thinks it was a good choice for them because the kids love playing with it."

All have different characterpersonalities.

One loves to sleep, another loves to play, but all of them loves people.

C: This person has an aquarium with two fishes.

"An" is always used before words which start with vowels.

He had one for 6 months, then bought the another one.

D: This person haves a parrot.

"Person" is a singular noun so it's uses "has. "Have" is for plural nouns.

But a few weeks ago, it stopped eating and talking.

But the person talkcustomer says that he already has a dog andso he mustn't toshouldn't buy a new pet everyach time he visits.

So he buys a new toy for his dog thereinstead.

So they went to the city shelter and tookchose a dog there.

Be careful of using "there" too much.

A: He has a dog for two years already.

He has had a dog for two years already.

He thinks it was a good choice for them, because they have a big house with a garden, so the dog has a lot of place for playing.

Usually pets are referred to as "it" unless it has a personal relationship with the subject/speaker, then use "he" or "she".

All have different characters.

Needs a subject.
They all have different characters.

One loves sleep, another to play, but all of them loves people.

...all of them love people.

C: This person has aquarium with two fishes.

This person has -an- aquarium with two -fish-.

D: This person have a parrot.

This person -has- a parrot.

But the person talks that he has a dog and he mustn't to buy a new pet every time.

But the person -says- that he has a dog...

So they went to the city shelter and took a dog there.

Unclear if they took the dog -to- the shelter or -from- the shelter.
Say "took a dog -from- there" if you want to denote that the dog was adopted.