Alligator clips with wires already attached is nice to have but can become loose and short stuff, unless you get insulated alligator clips. Getting the right type and style of alligator clip is nice, some have a small wire that loops around to hook onto some surface mount tech (smt) or through hole components.
Soldering iron, solder, tin the pads or wire before soldering wire, drug store 90+% isopropyl alcohol is nice but not necessary unless there is corrosion, dollarama paint brush with the brissles cut short for extra friction (if necessary).
Take a picture of the electrical label, that will tell you everything you need to know.
You can buy battery holders of various sizes, you can buy a battery holder for 18650 and 21650 and D's and C's and A's and AA's and AAA's
Fastech.com
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