These are tips to help transmigrate your daemons faster.
Transmigrating daemons are often turned into better daemons which are more preferrably used. In this case, most of the time, the original daemon skill levels can be ignored, since you won't use them in your team anyways. (e.g. Original form of Lady Suzuka has no skill, so there is no concern on skill level up).
Fusing daemons with specified magatamas are helpful (e.g. Kyu fused with Kyu Magatama), since it does help them level up faster.
Also, using the sealstone magatamas are useful in leveling up the same type of daemons, regardless of the skill. For example, you can use the Hare of Inaba magatama to fuse with the Goddess of Misfortune, and the experience on the
Goddess of Misfortune will still increase, greatly. After all, it is still a Divina 4* Magatama, and the effect should be the same (aside from the skill level up).
Please note, whenever you successfully transmigrate a daemon, they go back to level one, and everything is reset for them. However, they will now scale better when leveling, and become more powerful more quickly.
Only certain daemons can transmigrate. Most of those do so at max level, except for a few, such as Barbetta, Lilith, Goddess of Misfortune, and Goddess of Poverty (at levels 8, 16, 16, and 16 respectively).
Also see: Transmigrating Exception Daemons