What kind of clothes do they wear in Phuket?

Well according to this online newspaper, it's pretty warm and extremely humid, so I'd say as little as possible... I guess cotton clothing. I've posted the link to the Phuket Gazette below, and you can read up on it :)

I can only speak from personal experience as a tourist, but my mistake the first time to Thailand was to bring clothes that were too heavy/thick to wear in Thailand. I'd been to Australia, so I knew enough not to bring stuff like denim jeans etc, but even cotton chinos, light casual jackets etc were useless 99% of the time. I think I wore them for travelling on the plane there and back, and that was about it. Phuket would be around low thirties centigrade at the moment, which is still plenty warm. Just bring the lightest clothes possible, plenty of casual stuff (t-shirts, shorts, sandals etc) and as Ronnie says, leave your suitcase half empty. Thailand generally and Phuket in particular is strongly geared towards the tourist industry and they have plenty of clothes for sale for the larger westerners who visit. That's not a reference to you so much as me - I'm 240lbs and I had no problem buying stuff to wear. Travel lightly, leave loads of space in your luggage, buy what you need as you go along.

In Phuket, the weather is hot and dry. The BEST is Cotton made clothes. They are wearing a pants,skirts and blouses or T-shirts.

I would just stick with cotton. T-shirts and shorts are fine. Thais are used to seeing tourists in very casual clothes.

I see is no much clothe in Pathong. Is were bikini and swim sute walk along street. Is look like 'less is more'! Good see body acceptance, no afraid like Thai peoples.

Phunket is hot and shine place better wear cotton,t-shirt,

bikini,short and dont forget life jacket if there tusunam coming

... :p