There are some opponents I cant battle such as Goo Hund, Kiyo, Spirited Shrine Coin, Tempest etc

Were these special opponents for events? and if so will I ever get a chance to battle them again?

There have been past 'Battle Week' events where retired challenges such as those from events have returned briefly, but they do not always have the same loot (in case you were looking for any special loot)

There's a few that appear in battle quests too, but not the ones you have mentioned. Hope that helps? :)

Kiyo and Tempest will probably never come back because they were Global Bosses pertaining to specific events. Tempest is a peaceful NPC now when before we were fighting her because we didn't know that, and Kiyo was a disturbed spirit that has since been calmed.

As for the other two there's a good chance they will, but probably not anytime soon since they're pretty "new" event challengers and there are other older challengers that people have been begging for. It's also worth noting that you win against an opponent in BQs it doesn't count in your stats.