Brett, to be traditionally published, if that is your goal, you don't need someone to illustrate your words. This does not benefit you. Agents want to see a publishable manuscript. Editors want the same.
Here's why: You are an unknown and your illustrator is an unknown. Editors often pair up unknown authors with illustrators who have a following. That's a built in market for your words.
When you present the work together, it's assumed you intend to be a team. It is not seen as more professional or more polished than someone who presents only a manuscript. Polishing a manuscript is a matter of having it critiqued by people who understand the industry and have an ear to the market. To polish your manuscript, seek a critique group or post it to the critiques section of the boards. An illustrator's perspective can be invaluable in this process, but if your intent is to be taken on separately, you should both submit this way.
The illustrator can absolutely use pages done for your story as portfolio pieces for submission, which might get someone interested in your work. But there is no benefit to you in submitting their art with your manuscript.
So you won't be discounted as a team by everyone, but being a team narrows your options and doesn't offer much by way of benefit for either of you when you submit together. I hope this all makes sense.