Zyra and Sion get +5 gold for killing each other (Plants vs Zombies)
Nidalee gives lower level champs passive 1 exp per second. (Since they are younger and she is a cougar)
Leona does 1 less damage to any champ wearing sunglasses or have their eye blocked (lee sin). Also her spells make Zyra grow larger for a few seconds.
If Maokai is close to Zyra he gains 1 extra MS.
Fizz's ult can "eat" champions with small models when they die, leaving no corpse.
There are also many secret emots for certain situations and rival champions.