teehjaeh has hit the main points. 4 acres and 25' is a substantial pond. Any idea what your bottom temperatures are looking like?
Were I in your shoes, I would definitely stock SMB.
I would avoid NP, for the invasive species reason that others have covered, and also for the fact that they might reproduce and fill your pond with stunted 14" pike. Not a fun situation. TM could be cool, but you have to remember that your pond won't be able to support a large number of them, and that they will probably snack on any WE/YP/Trout you stock, along with probably some SMB.
WE/YP are both a solid idea. As others have pointed out reproduction might be an issue, but they make a put-grow-take fishery. I would use YP and no WE myself, for a couple of reasons. I find YP much easier to catch when ice fishing than WE, WE apparently grow very slowly in ponds, and WE don't hit a large maximum size in ponds. I believe that feed-trained YP can also be purchased from some hatcheries.
Trout might or might not oversummer in your pond. Were I in your shoes, I would put in maybe 30 RBT and see if they make it through the heat. Brooks are apparently more temperature/oxygen sensitive than RT, and experience has taught me that Browns can be very tough to catch in small lakes. No idea how Splake/Cutthroats do. RT are a good ice fish, and I've heard that Splake are too.
