Sundae's Links
For Sundae, Dyna was the perfect target for them -- young, innocent, and the sort who doesn't ask questions about the wishes they grant until after the deals said and done. The constant failure and time loops that Dyna had gone through in order to fulfill the wish that Sundae required has allowed the pokemon to amass a great amount of power, bringing them to status as a proper deity in many timelines.
In this one, however, Sundae found themself demoted after being caught by Sascha. While they can't go and scheme like they used to, they have fun bringing Dyna and Sascha to strange worlds, especially enjoying the reactions Dyna has from all of this.
All and all, Sundae knows how to get under Dyna's skin, and has a lot of fun doing so -- even if the sorts of things they pull today aren't nearly on the same level as they've done in the past.
Being used to forward a goal centered around Sundae's quest for recognition as a deity, and innocently accepting Sundae's ability to grant them his wish at a very, very hefty cost, Dyna's viewpoint about Sundae is overall negative.
Despite this, as Sundae is now one of Sascha's own, Dyna has slowly laid aside some of his grudges towards the pokemon. Regardless of time, though, he never expects himself to fully trust the wishmaker again, and always has an eye open to ensure Sascha (and himself) don't get involved in more than they ask for.
Sundae's first encounter was surprisingly tame -- in a timeline far off from the one that they are in now, they would learn of her through her recent passing. This would be the first of many times that Sundae would see her meet her end, thanks to Dyna's innocent, but dangerous, wish. And, after watching Sascha live, die, and live again, and through that, gain power through each timeline? Sundae had no reason to dislike the girl, being a key part to allow this cycle to continue endlessly.
Thus, it becomes a surprise to them when, against all odds, Sascha completely turns that cycle on it's head, and manages to capture Sundae. And while it's not to say that Sundae dislikes being one of Sascha's pokemon, the Jirachi knows that in time, they'll be able to outwit her and be freed once again.
Except, as Sundae grows to know Sascha, truly so, they realize that they have more in common than first assumed. And because of that shared desired to be in the spotlight, Sundae slowly abandons their desire to break free, and starts to help Saacha out more earnestly, even if their suggestions are suspicious at best.
Sascha does not grasp the depth of what happened between Dyna and Sundae in the slightest, and bears literally no grudge towards Sundae for using her in other timelines--frankly, she finds it difficult to believe anyway (after all, her power is limitless, nothing could kill her, as far as she is concerned). She frequently takes advantage of Sundae's ability to fulfill her own wishes, and views them as a valuable teammate and resource.