Would Twig be able to call in a favor from Dialga since she saved him? Or would bringing her back from not existing already be that favor?
Dialga considers them even in terms of debts owed— when Twig and Kip (and the Future Trio by extension) saved him from his growing madness by restoring Temporal Tower's stability, he felt he owed them a life debt. But when it comes to Twig, Dusknoir, and Grovyle, he satisfied that life debt by bringing them back.
With Celebi, he still owes her indefinitely because she's the sole reason the Dark Future wasn't a wasteland of unmoving pokemon frozen in time, and she's constantly cashing in on that fact. "Heyyyy Dialga! I want to go on a vacation in an alternate timeline but Palkia's being so mean and won't let me cross the spatial aspect of the journey :(" "Explain to me why I would help you disrupt the fabric of space-time for a leisure trip." "Remember how I maintained the flow of time all alone for ages when you were spending your time stomping on mortals instead? 🥺" "... I'll create a dimensional hole..." "Yayyyyy! ☺️💕"
With Kip, he still owes the little guy a life debt that he only barely started paying off by restoring Twig in such a way that she would be there with him in the Present. As Twig puts it: she's Kip's apology gift. Dialga still owes Kip— reviving someone who was already set to be revived barely scratched the surface of what he needs to pay.
Kip could call in unbelievable favors from Dialga, but he doesn't know that he's got a blank check written out to him by a major deity— and if he did learn this, he wouldn't ask for anything because he doesn't want to take advantage of Dialga. He doesn't see Dialga as owing him anything. In his eyes, Dialga needed to be saved, Twig and Kip saved him, and Dialga saved Kip from a horrible life spent without his best friend. There was never any debt in the first place from his perspective, and if anything, he owes Dialga.
