But back on topic: Confuse Ray is awesome. Even if I only used it twice in a match, that's still twice as often as I could have possibly used Explosion. If I know I don't like using Explosion, which we've established, I've gotta put something in that extra moveslot, and Confuse Ray has waaaaay more utility than Mega Drain. Are you opposed to Confuse Ray in general (as in, you would never use it on Lapras for instance) or just on Gengar?
IIRC Confuse Ray gives 1-4 turns (3/3/1/1 ratio) of "X is confused!" followed by one turn of "X's confused no more!". Tell me if I'm wrong here, because it's crucial to my argument.
0.375 * 1 * 0.5 + 0.375 * 2 * 0.5 + 0.125 * 3 * 0.5 + 0.125 * 4 * 0.5 = mean 1 turn of hitting self in confusion per use of Confuse Ray. It's less if they're paralysed, or if they switch out before the 4 turns are up. (EDIT: Ugh, I noobed, it's 1/1/1/1, and the mean is 1.25 without paralysis. It's still under 1 given paralysis (0.9375) and under 1 given that they switch out before three turns of confusion.)
But Confuse Ray takes 1 turn to use. So, on average, using it doesn't get you anywhere. Using it is solely good for increasing variance, which is worthwhile only in either a) very fast matchups where you always lose but a single extra turn would make you always win, and the situation is such that this is worth the high risk of dying for free, b) attrition matchups where you kill them at least as fast as they kill you but they have recovery and you don't. Using it to ease switches is rather suboptimal; they're only going to spend 1 turn confused (since you're presumably switching to a counter, and so they'll switch out), so 50% of the time it has no effect (and you'd have been better off just hitting them on the switch or double-switching), and 50% of the time it'll be a Wrap switch that can't threaten to stay in and can't be used vs. a slower opponent that's already in.
Does Gengar have any matchups that fall under a)? Yes. Mega Drain Gengar vs. Rhydon, and to some extent Thunderbolt Gengar vs. Psychic Starmie and Night Shade Gengar vs. Zapdos/Jolteon. The first - and clearest - your Gengar cannot take advantage of thanks to its lack of Mega Drain. The second and third, on the other hand, are cases where even that single extra turn may not actually save you; a single Starmie Psychic has a 45.7% chance of preventing a cold Gengar Thunderbolt 2HKO (by either critting, and killing Gengar instantly, or by causing a special fall), and Zapdos and Jolteon have high chances to crit Drill Peck and Thunderbolt while Night Shade cannot crit. Overall, I'm not sold, particularly since in either case you take a high risk of getting one less hit in for no benefit, and as such these are very-high-risk gambles that are also situational.
Does Gengar have any matchups that fall under b)? Yes. Non-Thunderbolt Gengar vs. non-Psychic Starmie, and Gengar vs. Chansey. The first is not an issue for your Gengar, as it has Thunderbolt. In the second, Gengar's chance to beat Chansey is abysmal even with Confuse Ray, and a move that helps much more is... Explosion.
So yeah, I think Confuse Ray's not great on Gengar. It's an "option", I guess, but only over one of Gengar's attack slots. Never over Explosion. The only thing that could possibly be worth losing Explosion would be a successful surprise with Mega Drain.
Do I think Confuse Ray's bad on other things that get it? Well, I think Ninetales, Golbat and Magmar suck regardless of what they're using (Ninetales has a miniscule niche), so we're basically just talking about Lapras. I think it's decent on Lapras thanks to case b); Lapras has the unfortunate reality of bad matchups against all three Recover users, and Confuse Ray helps luck all of them (whereas Hyper Beam only helps against Chansey and Alakazam, not Starmie). It's definitely not as ironclad as Blizzard and Body Slam, though. If I were dropping Thunderbolt, I'd probably drop Confuse Ray for Hyper Beam since CRay has at most like a 5% better chance than HBeam and HBeam can improve chances compared to Confuse Ray by over 25% in some situations. CRay + Rest is usually an illusion since as mentioned it on average doesn't use more opposing turns than are required to use it.
I agree that confuse ray is an underrated move, because all it does is giving matchups a higher chance going your way. It's just that I (and great parts of all players) prefer the utilitly of other moves (explosion in this case) over that. Cray on lapras is mostly there to let chansey (and other) matchups go your way and for the lack of better alternatives (sing catches chansey and alot other things too, but is unreliable. And what else is there? Rest?).
Confuse Ray doesn't give matchups a higher chance of going your way. It gives matchups
that you were going to lose a higher,
but still under 50% chance of going your way, and matchups
that you were going to win a
lower chance of going your way. Slight exception for the aforementioned long attrition battles where an opponent has recovery; those can at least theoretically go over 50%.
Confuse Ray is a pretty cool guy. eh stops Recover as you switch out and doesnt afraid of anything
What's the point of stopping Recover as you switch out, when you've also stopped yourself from damaging them?
EDIT: If anyone wants a full analysis for the matchups I'm talking about with and without Confuse Ray, I'm game. Except in the case of Lapras vs. Alakazam, that matchup's a bit ugly.