Technically, all I
need are the skates. I don't even need the bag.
My major essentials for skating include skates, guards, soakers, trouser socks and a rag. I bring tissues and a water bottle onto the ice. There's a skate hook on the outside for when I change out of my skates. (Use it to loosen the laces.)
I have a screwdriver and screws in my bag, just in case. A sharpening stone to hone the edges when they start getting dull. I have a stopwatch in there to time music or do interval training, but it's a leftover from years ago: I've been using my phone timer lately; it works better.
For coaching, I carry a portfolio with my instructors manual, MITF book, competition / test forms and a variety of evaluation forms plus pens, pencils and markers. A few sheets of seasonal stickers for little kids are usually accessible. I've been tucking my ipod and headphones in there lately, which makes it easy to find. At times, I tuck a skating book into the pouch to review. A few large index cards for choreography notes, and a CD wallet for students' music CDs. Champion cord knockoffs with clips, a hockey puck for balance drills, and four small rubber duckie-penguins for teaching tots. Plus extra markers.
However, my bag is always overfilled because I use it as a locker/portable office. So, I have laces, spin trainer, some money, a first aid kit, Advil, an awl (to start screw holes), insoles w/ scissors, brush & hair accessories, hand sanitizer, extra tissue packs, boot covers, extra gloves, appointment book/receipt wallet, blank notebooks (for students), extra headphones, a small plug-in speaker for my ipod - it's like watching a clown car explode ...
See the little white-and-blue ball at the bottom of the photo? It's a kids sock filled with silica gel and activated carbon - absorbs moisture and smells, so no problems with rust or stench.