One of my favorites with Freddy, which is more or less guaranteed to work on people you're playing for the first time, is this:
After a jump in punch you can use B+2 xx Freddy Fingers. It doesn't combo, but the overhead followed by a quick low is something most people just don't see coming if they're not acquainted with the character. Plus, despite it not comboing, a lot of people don't know that either so it seems as though most people get hit by the FF when the B+2 connects anyway because they don't crouch block after the first hit, they probably just standblock.
The nice thing is, Freddy Fingers on hit gives you a bit of space and advantage so if they get hit by the low you're in a pretty solid position. I don't think the frame data is out, but it seems like, if you hit with Freddy Fingers off a JIP, if you use 2, 2 it beats some moves that aren't 6-7 frames. You can cancel this into EX Spike for a combo or instead of even risking the 2, 2, use it as an opportunity to NMS xx Teleport away.
To be completely honest though, the real reason I use B+2 xx FF is because after getting someone with it twice (and as I said, if you're not well acquainted with the character, and not many people are, it'll work at least twice) I immediately go in for the B+3 xx EXClaw for a huge combo. By that point they're thinking I'm going to B+2 xx Freddy Fingers all day because it works pretty well.
He has pretty nice mixups. Also, it seems like FF is safe on block so it's not like you're gonna eat a full combo if they do actually block it.