Aliasing kaiju → species:kaiju
Link to alias

Reason:

It's a species of giant monster.

Kaiju already is a species tag, so that would basically alias it to itself.

Tag types are differentiated by color, here's the list: https://e621.net/help/tags#Tag_Types
(No aliases needed to change them, can be done in the tag edit.)

Genjar already said everything important, I'll go ahead and deny the alias so it doesn't clutter up the list.