Although you need an ordinary fence of some kind critters will eventually figure out a way over, around or through it. Hakubishin will dig under, Raccoons will go over or Innoshishi can just push it over with time or numbers. However none of them will tackle an electric fence more than once or twice.
You need to site the wires at about nose height for the creatures you want to defend against so they can sniff the wire when they first encounter it. 10,000v delivered to a curious wet nose is a powerful deterrent and will quell their curiosity pretty swiftly but as the amperage is low it won't cause any harm.
When choosing an energiser I'd recommend going for a foreign unit rather than one of the Japanese ones available in home centres, they are far better constructed, have better option and will last a lot longer. Farmage
sell Stafix energisers and I'd personally recommend the XS range as being the most flexible. You can connect them to a deep cycle battery until you can run a mains cable to it or you can hook up a solar panel to keep the battery topped up. Don't bother with the AN series, it's under powered and too limited same goes for the one with the built in solar panel. Buy a bigger one than you need to allow for future expansion.
A word of caution if you do order the energiser from abroad, I originally bought a solar powered unit with internal battery from the States and it worked well until I had to replace the battery after 2 years. The shipping costs on a new lead acid battery was more than the unit cost initially and that would have needed replacing every 2 years. Unfortunately you can't get the exact same size deep cycle battery here so I had to run it with the battery outside the box that led to all sorts of problems and if the unit needs servicing then you have to pay the return postage which can end up making the unit cost ineffective over buying one here.
You can buy wire from your local home centre and probably insulators too and most likely they will stock gate handles. You'll legally need a warning sign. A fence tester is probably worth having for easy checking from time to time.