In Photoshop elements you can create talk and thought bubbles using the shape tool. Create a new document and put the bubble you want into it. save it as a transparent gif or png.
The trick is to bring the file into premiere elements using the import file dialog in the titler. This way you can apply a title style to the object. I also like to add a the text at this point as well, that way the bubbles that you create are reusable. Another trick to reuse a talk bubble that has the arrow pointing at your subject on the bottom left. but let's say you want it to use it on another title but you need the arrow on the bottom right. After you've imported the bubble into the titler you can flip the object horizontally by clicking on the left handle to resize and dragging it straight through the other handle to the right.