The most obvious choice is Red Scorpion... Dolph mostly in short pants and nothing else, plus the best shape of his whole careeer. Yum!
Then there's Army Of One. Ok, he wears a shirt, but a very nice red one.
Showdown In Little Tokyo - Dolph as God had created him. Nice butt!
Hm... I like Men Of War very much. Not only nice Dolph shots but also a good movie. Well, if you like movies like Arnie's "Commando" and such.
I guess those were the best movies if you go for the "drool factor". There are others with nudity but he never looked as good again.
Stay away from Knight Of The Apocalypse. Not only a totally boring movie but he also never takes his shirt off. Not once.