Which is the correct sentence for reporting the sentence?

Kah Meng is poor at his studies. He is not well-liked by his classmates.

1. Not only is Kah Meng poor at his studies, he is also not well-liked by his classmates.

2. Not only is Kah Meng poor at his studies(,) but he is also not well-liked by his classmates.

a) Which is the correct sentence in reporting the above sentence in bold? I think it is 2.

b) Is a comma needed after 'studies'?.I don't think so. Am I also correct?

Thanks.

1. Not only is Kah Meng poor at his studies, he is also not well-liked by his classmates.

No 1 is correct inclusive comma.
An example with "but" is: Not only that, but I also think that.....

februar, no teacher

2. Not only is Kah Meng poor at his studies, but he is also not well-liked by his classmates.

This is correct. If you don't put "but", you have to have two clauses as separate sentences or put a ";" between them.
As far as the comma, we do need it.
Check this out:
Comma Rules - Grammar & Editing Wiki

__12__ Do not place a comma before the second half of a correlative-conjunction pair (not only...but also, not...but, either...or, or neither...nor) unless each half is followed by an independent clause


A good lover not only accepts but also treasures his or her beloved’s flaws.


Not only did the monster exist, but also it was under the child’s bed.


Either you are a winner, or you are a loser.