Meade DS-2000 refractor
The 26mm in that scope gets you only 26x for magnification (assuming you have the 700mm focal length 80mm model) which is much less than needed for decent image size on Jupiter. For a scope that size, you could probably handle 120x -140x without losing decent image quality. A 5 mm or 6 mm eyepiece would get you there. (See my article Telescope Eyepiece Questions for more info on eyepiece math and more.)
Yes, you should have also gotten a 9.7mm (72x) SP, according to Meade. That would be basically a mid-power eyepiece in this scope.
The Series 4000 are actually the same basic eyepieces as the SP supplied with the scope, but with metal bodies and more robust construction. The Series 4000 plossls have long been the standard in a $50 Plossl.
What I would do, here, assuming you can round up that 9.7mm eyepiece, is go with a 2x barlow, such as the Meade 126. When used with the 9.7mm eyepiece, you'll get a very reasonable magnification of 144x for viewing planets. That's about as far as you want to push an 80 mm achromat in this quality range if you expect any kind of image quality.
Not to worry, this is the place to ask questions and I am more than happy to help.
You really do need a low, mid and high power magnification range to cover all the bases in astronomy. You could do this with three eyepieces or two eyepieces and a barlow which gives you basically four magnifications, as long as you are careful not to overlap. On your scope, adding a 9.7 eyepiece and the barlow would do the trick. Sticking to joust the 25mm and a barlow will get you 56x - way short of what you need to make the most of Jupiter.