Tesla was one of the first bands in the 80's to do full on acoustic tours, and they kinda set the stage for all the MTV shows they did where bands would come in and play acoustic. They had a really small window when they were near the top, but came in late in the 80's and things were changing to grunge by 92.
One thing that Tesla did, or didn't do, was they weren't using drum machines. They really weren't a true hair metal band because they never did the whole make up and gaudy outfits but didn't fit into the pop category either. To me, they were just a really great rock band.