The interesting part is that greens card advantage is tied to its creatures, caring about them dealing combat damage or their power
As a two prizer deck, giving up one prize is rarely game losing, but resetting 3 energy back onto the board enables Raichu V to be a serious one shot threat in the late game, something that Miraidon has been sorely missing since Flaaffy rotated
Roosevelt Hordemaster is a two-mana 1/1 that gives all of your other goblins +1/+1, which is nice
While that's not the most terrible idea, the likelihood in a Niv-Mizzet deck is that the other spell you're casting is a burn spell that could do the same, and I have to feel that you're going to be better off casting it by itself, rather than putting all your eggs in one basket
Graded Population Report: Horsea #67 Visualize the distrbution of grades in the chart
I did my best searching for them with this Scryfall filter, but I'm certain I missed a few