Bittersweet Ending: Although they save the world, Ken can no longer talk with Shiron. However, their friendship is still implied. Afterwards, Ken moves to America, leaving behind his friends, to face the American champion, the boy he knew from earlier.
The Chosen One: Ken, Leo, Kaoruko and Ririko are the Four Sagas, chosen by the four elements.
Eldritch Abomination: Jabberwock/Necron. His influence is enough to cause all Legendz to go crazy just by existing.
Expository Hairstyle Change: Leo Engokun. Just before he makes his big entrance in the Legendz Carnival, he slicks his hair back into spikes.
After learning that the Golden Soul Figure can power up Shiron to ridiculous levels, he actively decides not to use the powerup ever again, because winning battles using outside help won't help them grow. To his credit, he and Shiron wipe out like 500 Mooks and a Triton by themselves before the arc is out. They use it again, in the battle with Necron, as a form of All Your Powers Combined with the other Sagas.
Interestingly, the Golden Soul Doll isn't actually activated at all in the entire manga; Ken uses its power, but refuses to use the Legendz. It makes one wonder if the series could have had a better ending had he just Reborn'd the thing...
Mythology Gag: During the Legendz Carnival, one of the souvenirs Ken buys is a key-chain with a Windragon on it; it looks just like Shiron's Fun Size Mode from the anime.
Ninja Pirate Zombie Robot: While invading a high school, Ken encounters Ninja Werewolves. (He even notes how ridiculous it is.)
Serious Business: Of the "The creatures are real and hold the power to save/destroy the world" type.
Legendz, the anime, provides examples of the following tropes:
A Boy and His X: Played straight with more or less the entire lead cast. With so many Mons coming out of the woodwork, there's a good chance of finding a boy (or girl) learning important life lessons from it.
Ambiguously Gay: Crocodile Dandy and his male room-mate Salamander. He gets all misty-eyed, complete with Bishie Sparkle, when his "Aniki" Shiron shows up and drives what appears to be a pink minivan around.
Anvil On Head: Used on Shiron to help snap him out of Colonel mode in the last two or so episodes.
Bittersweet Ending: Shiron defeats Jabberwock, but all of the Legendz disappear, and are permanently forgotten by everyone.
Blessed with Suck: Ranshiin somehow managed to strike a deal with dark forces for great power and knowledge, including the ability to see the future. Unfortunately, the deal gave him a Weaksauce Weakness. Despite being a Wind-element creature, exposure to the open sky causes him to both lose power AND experience debilitating pain. (Whether this is the curse itself or a side effect of purification is up to debate.) To the point that, despite him not only having wings and being able to fly and having Elemental Baggage, he spends his time in a cramped wind tunnel and has to use a little hover pod called the "Bird Cage" to get around in.
Breaking the Fourth Wall: This is done numerous times, mostly lampshading the obvious clichés that the show is going through. "What kind of an anime is this??~!!, 'Warrior of Light?' That's not written in the script!" and to a lesser extent the part where Shiron talks about how hard it would be to make a Legendz anime.
Breather Episode: The "Ed and Fired Giant in: Adventure of Fired Brothers!" episode.
Broken Pedestal: Ms. Hepburn used to love legendz, then she became disenchanted with them and the people who hang out with or research them. This includes her Papa.
A lot of the lesser legendz, namely Dandy and Salamander, can control their respective element but not produce it. For example, Salamander produces oil from his tail and lights it on fire from some other source and Dandy can't produce water, but he can cause tidal waves when near the ocean.
Also, all legendz get antsy when they can't get regular exposure to their element of choice. Windragons love windy areas, Goblins constantly dig and mine, and Devour Gators such as Dandy get some serious scale itch when not regularly moisturized.
Elemental Rock-Paper-Scissors: Fire beats earth, earth beats wind, wind beats water, water beats fire, and the usual light/dark relation. This is even used in a minor Batman Gambit involving attacking each of the protagonist's homes with an element they are weak to. It would have worked if the apocalypse didn't start right that second.
Evil Twin: The two windragons. It's actually more complicated than that, given they're two halves of the same person.
Humans Are the Real Monsters: Played with. Some of the Legendz had a very strong intention to wipe out mankind because Humans Are Bastards. While none of the protagonists was evil (none of them even poacher, woodcutter, or litterer!), some people let the evil Legendz control them, and others found the strength to resist. Maybe, SOME humans are bastards?
Idiot Hero: Shu. Then again, he's like... 10 at best, so we can forgive him for it, but he's still noted for being a very... Silly person even by his peers.
Interspecies Romance: Haruca goes on a happy date with Shiron. Shiron almost gets forced to marry Meg's mouse counterpart. Shiron has Dandy clearly head over heels for him. (See a pattern?) Then BB and Greedo... The less said about Ed and Linda the better.
Nice Hat: Shiron's flight cap, which even has an episode centered around it, and to a lesser extent the Original Fire Saga's extravagant red wig.
No Fourth Wall: The anime constantly calls attention to it's own insanity, especially through Shu. Episodes often begin with the phrase "What kind of show IS this?" and throughout several of the episodes Shu comments, "What a typical anime _______" In the last episode, the characters refer to the script, unsure of the true ending.
Oh Crap: A chain of these are set off right when the Legendz War begins. It starts by Shu's mom becoming a casualty. Shiron has one of these when he sees Shu has gone into shock. Garion and the others also have an Oh Crap when the wind suddenly and violently stops blowing. And then Jabberwock gets summoned.
Power-Up Food: Garion and Garlic Hamburgers for some reason. They end up curing her Laser-Guided Amnesia as well as her garlic breath being used as a [[Understatement somewhat silly]] finisher on a vampire she fights the same episode.
Rousseau Was Right: None of the human characters are genuinely evil. The bad guys just manipulated by the evil Legendz.