This mirrors the TCG where blue eyes get good cards, DM gets mediocre cards and red eyes gets trash. Here kaiba gets good skills yugi and joey gets useless skills.
Reference is fine. The problem is the skill is weak. It should be twice per duel and turn any gaia and any BLS into super soldier. Turning gaia into vanilla BLS is so useless.
The word "contains" here does it mean the vanilla Gaia TFK only or any Gaia TFK monsters?
This would determine whether this skill is bad or acceptable.
If the text uses "is" instead of "contains", then for sure it refers to the vanilla only.
Needing a "Kuriboh" monster is fine, Sphere Kuriboh is still a pretty good card to have in a deck.