Believe it or not, you may not have a pudgy stomach. In fact, you actually sound quite normal. What it is has to do with the way you walk and hold hold yourself. If you're like me and slouch ever so slightly as you walk, it'll make your tummy look a little pudgier. But if you stand up straight and puff out your chest slightly, it'll make you look smaller in the stomach. I know it seems like a bother to do all the time, but people have been doing this for centuries really...
But if it really is pudge and you just want to do some exercise to get rid of it, crunches and leg-ups are great for working out the stomach. The crunches handle the upper abdominals while the leg ups handle the bottom. Push-ups are also great, because they work out the whole body, tummy included (trust me, I know ^^; ).
It should be noted that it's kind of impossible to get a truly flat tummy unless you want to go for washboard abs. >.>
Fem!Matsuoka Rin (Free!) - 95%
Grandmaster Robin (Fire Emblem: Awakening) - planning
Kamui (Fire Emblem: Fates) - planning