Yes, there are multiple RAVs that you can use to infuse Thunder into Buccaboo Ace. If you're following the build found in my Monster Infusion FAQ, you can use a Lv. 20 Pink Lily to transfer Thunder and Thundara. A Lv. 08 Zwerg Scandroid would most likely be the easiest source for Thunder, depending on how far you've progressed in the Historia Crux.
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