Are there hidden passives in the game?
 

I was watching Oddones stream and he mentioned if Maokai is near Zyra(both plants), their movement speed increases by 1 and if a champ is wearing sunglasses, Leona's ult is reduced by 1??
This true?
Can you guys list them if it exists?

Yes.

Yep, there's also a few others
Like the showdown between Rengar and Kha'zix.

yes its true. Leona's passive does less dmg to people with protective eyewear.

if you have multiple ninja on the same team there hp is lowered by 1 per ninja.

there are more

yes.

if zyra gets leona passive on her, she gets bigger.

The most noticeable is that, if there are multiple ninja champions (Shen, Akali, Kennen) on one team, they have their health reduced by 1. This is because ninjas work best alone...

If you play one of those champs a lot and know their starting health well you'll see this pretty clearly after a while.

Lee Sin does not impact this (he's a monk, not a ninja). Don't know about Zed.

Fizz's ult will eat all yordles (If it gets the kill) except for Heimerdinger and Teemo.

Leaving no body.

All champions and skins wearing sunglasses take 1 less damage from leona, and a couple like that.
Ninjas near eachother all have 1 less health.
None of them are game breaking.

if Pulsefire Ezreal does his taunt when Syndra's around, it will say its over 9000

If the ninja's have their medical skins I believe they are no longer affected by the hp loss.