Any point in Zangoose, other than a dex entry?

Shadow Claw/Night Slash would probably be a decent counter to double ghost Gengar and other ghosties. Shadow Claw is a good move and Zangoose double resists ghost attacks.

Right now, like WaterYouWading4 said, Zangoose provides a great ghost counter while it holds a normal type
allowing it to receive an immunity damage multiplier from ghost attacks. As well, it also muks up dark pokemon with fury cutter / close combat.

HOWEVER, zangoose's real power is not currently being reflected from the main series. In the video games, Zangoose has an ability called Toxic Boost, where when poisoned, has its attack stat multiplied by 1.5x. Zangoose also has access to a move known as facade, and when a pokemon is afflicted with a status (e.g. poison, paralysis, etc.) the power of facade doubles such that its base power is nearly as strong as hyper beam (and facade only requires one turn in the games!). Furthermore, facade is a normal type attack and so is Zangoose, so throw another multiplier in there for STAB.

Here he is in action:
http://replay.pokemonshowdown.com/gen7unratedrandombattle-573468657

Although the paragraph is not completely relevant, should pokemon go add abilities, zangoose will certainly gain some potential. At the moment I would not invest stardust in it.