Ganyu has a 2nd level CA that does aoe cryo damage and has a pretty large mv (so similar to Noctis in this regard). It has no icd so it can melt both hits. This can be convenient in overworld. Her E is a taunt. Her Q does dot and buffs cryo dmg, so she can be a support for Ayaka even (which seems to be a popular pairing). The Q has pseudo-quadratic scaling (not true quadratic scaling like Childe E). Some say Childe C4 can work with Ganyu for freeze and because Childe's passive increases NA level by 1. Given Fontaine introduced constellations that give +3 levels to NA, we believe Ganyu could benefit from such a constellation.
Ganyu's best cons are probably her C1 and C6.
Ganyu's signature Amos bow appears to reference Amos Yee. Other than that prototype R5, great magic, thundering pulse, even aqua simulacra can work, though they do not have as much synergy.
Temmates:
Example teams:
For freeze build she can use blizzard 4p. For melt build she can use wanderer 4p. If paired with Furina (for say freeze), she may be able to use Marechausse, but why bother? Blizzard gives more crit rate to her.
Ganyu's advantages over Lyney is that she has aoe on CA and can melt. But she may not have the same amount of dmg bonus as Lyney.
We assume talent level 10 on the charged attack. We also assume Ganyu is wearing a 4-piece Wanderer's with Cryo DMG Bonus (up to \( 46.6+35=81.6\) DMG Bonus). Note a 4-piece Blizzard Strayer gives less DMG Bonus. We assume that she is not using her burst, and we ignore weapon effects as in Xiao's case.
It takes 3 seconds for Ganyu to do a fully charged 2nd level shot. The DPS scaling for one level 2 shot is
Ganyu melt teams look like: Dehya-Nahida-Bennett-Ganyu (burn melt), Dehya-Bennett-Kazuha-Ganyu (anemo melt).
Melt Ganyu usually involves 4p WT and vaping her CA. This requires a pyro support such as Dehya or XL. Within Dehya's 12s E, Ganyu can vape around 4 of her CA. It is almost a coincidence that Dehya's E also procs 4 times within that interval... Anyways, even with C6 XL 14s window, in practice Ganyu will still vape around 4 CA (taking ~3s average to fire a full lv2 CA). Moreover, XL has a huge 80 energy cost, while Dehya's E is free pyro application (which has more range than Guoba). As such, Dehya can sometimes be more convenient for melt Ganyu (especially in overworld). Dehya's C2 (18s window) widens the gap even further, becoming the best, longest-lasting, and most economical pyro application over time in the game (as of 4.4).
But no matter how meta or good Dehya is, not even a goddess can save a miserable F tier depraved soul like Ganyu.
A naive calculation would assume for Ganyu melt just multiply her dps by 1.5. But that assumes you have 100% uptime on pyro application when in reality there is always a limit. Dehya's pyro app lasts 12s at c0. XL's pyro app lasts 10s at c0. Burning is not too reliable for Ganyu melt (especially since burning was nerfed in 3.0 beta). And anemo absorption off-field abilities (Venti q, Kazuha q) will not last as long as Dehya's E. So Ganyu melt will have a cd (unless you have Dehya c2).
Suppose within a 20s window, Ganyu can melt 4 CA, does 1 nonmelt CA, and the rest of the time is used for setup. Then the dps is $$x_m = 376.52*3*(4*1.5+1)/20 = 395.3$$
Usually her disco ball is only used in freeze comps where Ganyu has blizzard strayer for 61.6% cryo dmg bonus (as otherwise it can mess up melt teams). We assume level 10 burst for 126.49% scaling per icicle.
If there is one enemy, 10 icicles will hit. If there are two, 20 icicles will hit (spread between 2 enemies), and so on. This caps out at 50 max if there are 5 or more enemies. However, it is usually not the case that there are always 5+ enemies. Suppose there are 2 enemies in an average situation. In other words, suppose 20 icicles hit. But not all of them hit every enemy. They are generated pseudorandomly. To get all icicles to hit every enemy, one usually needs CC like Venti. Let's say in practice, about half of them hit every enemy.
The burst lasts 15s. The dps is
In practice, the dps will be much less, since not every icicle is guaranteed to hit the enemy.
As Ayato's burst is similar, a similar type of analysis applies for her as well.