I'm having trouble trying to decipher what the sizes of spinning reels are. Pflueger has different numbers than other manufacturers. So I guess what I want to ask is what size Pflueger reel would work best for shaky heads, wacky worming, and drop shotting?

I would just base it on the line/lure size recommendations.  What is the line weight recommendation based on the specs compared to what line you will be using?  You don't want to put 20 pound mono on a reel designed to hold 140 yards of 8 pound.  Same goes for 4 pound on a 10 pound reel... overkill.

30 or 35

There is no industry standard, a decent rule of thumb is line capacity and max drag, but it doesn't always work that way. Some of my of my smaller spinning reels.

Supreme 35              8/200           12 drag     8.8 oz

Stradic 2500             6/200           15 drag      9.2 oz

Cabo 30                    8/160           23 drag    13.4 oz

Abu soron 20             8/130          16 drag      9.6 oz

 

What are they............lol

Same situation prevails in larger sized spinning reels too.

There's variation among brands but generally spinning reels are basically classified 10-20-30-40 size.  Higher number = bigger reel.  A number like a Shimano 2500 is their idea of a size between the 20 and 30 size reel.  For the fisherman, it's a balancing act.  Larger spools have less line twist.  Smaller reels balance better and are handier.  My favorite is the 2500 size Shimano reels.  BTW, not many guys buy Japanese Domestic Market Shimano reels but if you do, their sizes tend to run about one size smaller than their US Market alternatives.

I really like the 30 size pflueger reels for bass fishing. Not too big, not too small...and light weight.