If you're drowning in revives, sure. SC Gengar kicks butt every second until it goes down, but unfortunately, there aren't that many seconds before it goes down. The only relevant time it can take a big hit is against Focus Blast Mewtwo, but then it can be a lifesaver if you're short-manning it. It's good against Machamp, but there are better options.
That said, this is a game. If you love it, go for it. Might not be ideal use of resources, but if it makes you happy, who cares?