I’m in two very different minds with this one for a teaser;
1.) Create something that stands out, if it’s a teaser, the aim is to tease, and then follow up with your full portfolio and more description later. So maybe something a bit different, maybe not even paper sized formats at all? A teaser trailer, web page, interactive piece? But not something too far that it detracts from the work and becomes about the format instead!
2.) The more traditional mini-portfolio route, these are always useful when there are lots of submissions, you can just run out prints of the ‘yes interview’ folder, ready to review with others, or bring in to the interview for reference. In this case, I’m with Yo, I’d use whatever format shows off your work the best, that can still be printed easily. Look at how your images and projects work before settling on a format that might not work for your work.
At the end of the day, you want to create enough to tease, to intrigue, to get somebody to want to find out more, so it depends a huge amount on who you are, how you want to represent yourself, and the work you already have.