Yes, you need a pitch deck, and yes, make it good. Investors want to be blown away by the opportunity, and by you as the person with the vision to make it happen. Eight slides is optimal - make the opportunity clear at the top so it's obvious what problem you're solving and why the market needs it. Every meeting with an investor is a review - take their feedback and keep iterating. There are tons of great examples online - do a deep-dive and see what kinds of templates and tone work for you. I advise startups on their comms all the time, happy to discuss.