How do I activate the runes and defeat the evil king

you need to have a pet with a 'natural stat' (base stat+level bonus+proficiency; that is, it ignores all equipment-given boosts to the stat, as those are 'added' to the pet) of the kind that particular seal wants that is above... 200 or so.

The translate text gives you the order using different terms for the four base stats (Str > Int > Dex > Agi is not the order that the seals are in)
you can translate the text and guess which word corresponds to which stat or you could check the walkthrough for which is which or something?

The King is easier with the seals activated.

Can't say much on 'how to defeat' since it would at least in part depend on your team and I don't know what yours is

Thank you for the advice I was able to beat him thank you so much!