In my experience there are not many condominium developments in Bangkok that allow pets. The reasons are smells, mess, and noise. Some people ignore the rule (as is the case with a lot of rules in Thailand) but this rule appears to be enforced.
I remember once when I lived in a condo in On Nut. The room on the opposite side of the corridor and about 2 rooms away was inhabited by a Thai girl. She was fine until her mother came to live with her. The mother had 3 very small dogs. They yapped at night whenever anyone walked down the corridor and were allowed free run of the floor during the day, depositing their stuff wherever they wanted.
After about 2 days of this a notice appeared pinned to her front door. It was a warning to remove the pets or unspecified further action would be taken. The housekeepers were livid.
No change. The dogs remained a total nuisance. Then I saw security staff at her door arguing with the girl. The next thing was their electricity and water supplies were cut off. The girl, mother and dogs left the same day, never to return.
I am not sure if this sort of response is typical but I expect it is.
There is one Condo Agency that I know of in Bangkok who knows about the condominiums that allow pets and can help find you one if that's what you need. Try this agency for pet friendly condos.