Some things to consider:
- Zam has about a 25% chance to get two special drops on a par Chansey before it successfully sings Zam. The worst case scenario here is not necessarily all that bad.
Cool, then what? You can also get a twave on another pokemon, which is nice, but you're still committing to never getting sleep while your opponent gets sleep. That's still bad. Your Zam needs to go real super saiyan and escape sleep altogether to get anything out of that situation.
- Along with that there is a cost to carrying sing on Chansey. You only get one out of tbolt, twave and counter. It will be considerably weaker against Lax.
- Also if it's ice only it obviously blows against any ice type, and if its toss only it sucks against Rhydon. It's your choice to wave t1, you can build your team accordingly.
Of course, but it's not a big sacrifice to make all things considered. The big weakness of Sing Chansey is the Jynx match up (unless you're not monoice Chansey, but then your set sucks and you're sad for other reasons), nothing to do with turn 1 twavers. It's not any weaker against Lax than standard boltbeam Chansey, given that you still have a slot for either twave or counter.
Almost all of the fills in traditional T1 twave teams aren't any good at punishing monobeam chansey - dropping tbolt for sing is only worse against Lapras/Cloyster (which still hate getting twaved), Articuno (which you still beat), and Starmie (which still doesn't break you and you're more likely to freeze it before it does anything threatening to Chansey; also it doesn't like twave either). The ONLY pokemon that really benefits from tboltless Chanseys is Slowbro. Hence his playrate last SPL.
The opportunity cost is very small. I've ran toxic in that slot in less serious teams, you really dont need the 4th move for anything crucial if your first three are soft+ibeam+twave.
- If Chan is sleep blocking Eggy or Gengar you can just explode on it. Even on a single sleeper team sacing Eggy to take out Chan can easily be worth it if you have strong enough special threats.
Oh yeah? Then you have an exploded pokemon and a slept pokemon vs 5 healthy pokemon. You're just going a full mon down. That's not good and not easily worth it. If you don't think this scenario is a problem I don't know what to tell you, you pretty much can't do any better out of the opening than a full pokemon lead w/ no significant luck involved.
- If your sleeper isnt Chansey, then against wave Zam it isnt that easy to get your sleeper in. Like, the standard play would be to go Chan to take the par then Eggy on the Psychic, but obviously Eggy gets paralysed, which is again good for Lax or Rhydon. And again, its not unheard of for Zam to just take out Eggy without taking the sleep. You also get the bonus chance to crit the psychic as it comes in for free.
Sure yeah, Eggy t1 on Zam can be risky, and it's the reason I much prefer Sing Chansey teams to old "big4" structures with lame ass Exeggutor. Eggy t1 a play you make to catch T1 Chansey while not being dead lost against T1 twave, it's not a play you make to counter T1 twave. I would never bring standard Eggy teams against someone who twaves turn 1.
- Ironically, one of the most dangerous lines for Twave t1 with Zam is for your opponent to twave you back. Chansey has its weaknesses as a sleep blocker, but its definitely better at it than Alakazam is.
The most dangerous line is hard Chansey on twave, full stop, nothing comes close. Remove that and then yeah no shit we go back to 2016 meta. Sing Chansey T1 is the sole reason we've moved on from turn 1 twave mirrors.
- Starmie is definitely weaker in the t1 paralysis lines, but its still an option you should consider. With a t1 switch to Chan against Starmie on turn 2 Chan can freely, twave, tbolt, icebeam or sing. So there isnt really a safe play there, except I guess go to Zam to absorb it. Generally I like to have Psychic on Starmie for that turn. Mostly because it stops Chan from just icebeaming. But Starmie's Psychic is not the same as Alakazams. Basically when you do this it should be because you have something special in mind. I wouldn't just throw this out mindlessly.
Starmie has even less odds of going super saiyan than Alakazam, yeah. It doesn't really do anything great for you if you're planning to twave t1. Not sure what this point is trying to argue.