Go to the website for each company. Look for links pointing to company info, employment, job openings, submissions, etc. See what they have listed and if they have any criteria you must meet for that job (in this case artist/designer/illustrator). If they use 2D for packaging then send a submission. Most times they will tell you how and what to submit.
I did a search at MS and Sony and neither had any openings for any type of artist at this time. Looking at the images they use to promote the games on-line, some appear to be traditional 2D and some look very 3D computer generated. It may take more on-line investigation than what I did and going to gaming cons that feature video games and their respective companies would help give you more information concerning the type of artist they use.