Definately learned something new today. Will steer clear of Wild Charge on the team of defensive Arcanines I am building, as it only helps the attacker gain free energy. Looking forward to part 2 to find out which charge move I should aim for. Also, I'll try to remember not to use my grass-type prestigers against my Arcanines if they have Fire Fang.
The "big 19" explanation – episode 9 – Arcanine (part 1) – The new move
Scizor 1: https://pokemongo.gamepress.gg/q-a/big-19-explanation-episode-6-scizor-part-1-typing
Scizor 2: https://pokemongo.gamepress.gg/q-a/big-19-explanation-episode-7-scizor-part-2-dps-so-close
Scizor 3: https://pokemongo.gamepress.gg/q-a/big-19-explanation-episode-8-scizor-part-3-unbelievable-fury-cutter
Arcanine, before the gen 2 release, is completely walled by Vaporeon. But now, with the new addition of the charge move Wild Charge, it can at least take out some to half of the Vaporeon's HP. And eventually with the legacy charge move Bulldoze, Arcanine is only fully type countered by Ground without being dangerous; however, Fire Fang does neutral damage to Ground Pokémon, and the Ground Pokémon usually have a low base DEF. Still, although Fire Fang is superior, it is a "quick" quick move for defense, and generates energy slower than Snarl, but with STAB, Arcanine can overcome this tricky disadvantage.
Do not think using Grass Pokémon is good, because they take super effective STAB damage from FF.
However, Wild Charge is still unlikely to kill Vaporeon, Poliwrath and other Water Pokémon with a high base STA, thus only giving them free energy to (using its Hydro Pump) defeat the Arcanine. This makes Arcanine easy to prestige with Poliwrath.
Gligar with WA/Dig is good to prestige if it is in the main series, but in the current game, it is not that useful because immunities are changed into not very effective.
Part 2 is coming soon!