You need a license to write the stat block of an existing character, even if you don't replicate existing material? Is the name that you cannot use without a license? If this is how thing are, maybe it would be possible to substitute the names with short descriptions like: "Primary configuration of a giant robot made up of three vehicles (able to combine into two other configurations fit for underground and underwater environments), able to fly due to its long cloak-like wings, and to fight with simple and double karate kicks, blades protruding from its forearms, two throwable axes that return to the thrower, and a powerful energy beam".