1. Having a lot of fun, we took pictures with Mina's camera.

2. Having a lot of fun, we we taking pictures with Mina's camera.
(Which one is a better expression?)

3. Making funny poses, I imitated monkeys.

4. Making funny poses, I was imitating monkeys.
(Which one is a better expression?)

5. Posting a lot of unkind comments, some students made fun of my pose.

6. Posting a lot of unkind comments, some students was making fun of my pose.
(Which one is a better expression?)

2 answers

Either of the verb tense choices in these three pairs of sentences work fine. I would tend to stick to the simple past tense instead of past progressive if the action has stopped and not continued.

Be sure to catch the typos:
In 2, "were"
In 6, "students were"
(corrected)

1. Having a lot of fun, we took pictures with Mina's camera.

2. Having a lot of fun, we we were taking pictures with Mina's camera.
(Which one is a better expression?)

3. Making funny poses, I imitated monkeys.

4. Making funny poses, I was imitating monkeys.
(Which one is a better expression?)

5. Posting a lot of unkind comments, some students made fun of my pose.

6. Posting a lot of unkind comments, some students were making fun of my pose.