Well, it kind of depends on the meaning of "don't need ADR".
If you mean, does the restaurant have a rule that says they won't seat you, ever, if you don't have a reservation, even if they have empty tables.....I don't think that applies to any WDW restaurant. Maybe V&A.
If you're looking for a restaurant that you can be pretty much guaranteed of getting in as a walk-up whenever you feel like eating...that's a very short list, probably consisting mostly of restaurants that don't take ADRs at all, like ESPN, Big River Grille, and B&C.
It's especially hard to get into theme park restaurants as a walk-up, since most of them are booked up months in advance, and if they're booked up, they won't let you wait for a table. You'll be turned away. This can happen at resort restaurants as well. I remember one Saturday night around 5 PM that I tried to get a dinner reservation at MK or anywhere on the monorail loop, and every single restaurant was booked for the night and not taking walk-ups.
It's an unfortunate fact of life at WDW that it can be tough to get into TS restaurants without ADRs. The best thing I can recommend is to call in the morning and see what's available that suits your plans for the day. You're going to have a limited selection of places and times, but at least you'll get in somewhere.