@Quakethorn honestly, not sure. It uses the type name and grabs the type name by going over BlockTypeRegistryModule
I have little experience with Sponge Forge mods, but I know the minecraft names use a minecraft:mob_spawner, so maybe Pixelmon uses pixelmon:healer or something?
Perhaps someone with more experience can help me out here, this is how Iām doing it currently (I already know there is probably a better way to do this, I was rushing here 
):
https://github.com/MarkehMe/Rson/blob/master/src/net/redstoneore/rson/adapter/type/sponge/TypeAdapterBlockType.java