I suppose that if 3. works with Guy, then Earth Main Defense Knowledge should work with Chiriku. Chiriku has +40% to defense and resistance to all Konoha ninjas, and Earth main has +40% resistance and +20% defense. So if Guy works, so should Resistance increase just as well.

I simply got Chiriku now, and I had the idea of making my Itachi+Sasuke Susanoo' (both) with Chiriku, and I was Lightning Main, then I had idea to switch to Earth and hope to have almost indestructible team, yet my Itachi still takes beating and has his health go down quite a lot no matter what, as if he doesn't takes any buffs consisting of (while this unit is on the field...). Maybe I just need further testing, but imo either Chiriku doesn't work, or there's something else...since I should have +80% resistance buff and +60% defense, but it feels that Itachi is just so weak on defense, makes me question whether something is not broken or incomplete. I tested it in Arena. It's hard to test when it is being affected by a lot of factors and there are all sort of players with different buffs and no buffs. I tested against my +/- equal player mate from the group, but I still couldn't tell the difference...at one moment his ninja hits 250 with my buffs on, the next he hits 405 without my additional buff from my main, and third time with buffs on again, he hits ~350... not a * clue if it works or it's just so * RNG within the stats and how they play against each other.

P.S. It's not mentioned, but Chiriku chase is from Knockdown to Lowfloat, since in my chase he does it, but it's not written on his bio information.