Originally Posted by Nikushimi

Only Rinnegan, Sharingan, and Byakugan are known to be the three great Doujutsu, and I'm certain Jiraiya didn't know of Mangekyou Sharingan when he made that statement, since that was a closely-guarded clan secret.

Also, having the superior Kekkei Genkai does not automatically make you superior; As we saw with Sasuke breaking Itachi's Genjutsu, the eye is just the weapon and requires actual ability to wield.

Also, Tien needs air to breathe, so no planet-destroying for him. Besides, he'll be too busy eating his own asshole from the inside once Itachi uses his mad Geass eyes to hax his brain.