A flashback from Kooper in Episode 3 shows Metal Sonic grinding a Koopa Troopa under his foot, resulting in first his spine audibly snapping, and then the unfortunate turtle exploding in a burst of blood from the pressure.

And when the heroes find the scene in Episode 4, they're pretty disturbed themselves.

That's a lot more visually gruesome than anything in Super Mario Bros.

Downplayed, but when Mecha Sonic kills the Koopa Troopa at the start of the series, all that's left of them after his energy blast is a visibly blood-stained skeleton that sways on its feet and then collapses, the impact popping its bloodstained skull off and sending it bouncing over to land at Mecha Sonic's feet.

Toadette reveals in Episode 3 that Knuckles saved her from Metal Sonic's attack on her in the opening minutes of Episode 1.

Sonic saves Mario when Oni Bowser seems poised to finally kill the Mushroom Kingdom's champion.

Romaji: Sūpā Kinoko) (also known as Magic Mushroom, Power Booster Mushroom, Power-Up Mushroom, or simply Mushroom) is a red Mushroom that serves a particular function depending on the game in which it is found. Its first and most common effect is causing Small Mario to turn into his super form, allowing him to smash through Bricks and take an extra hit from enemies. The Poison Mushroom can be considered its opposite, a mushroom item that hurts the player. Both this and the standard Mushroom are designed after the poisonous Amanita muscaria, with the shape resembling a button Mushroom. The idea for Super Mushrooms was originally believed to have been inspired by the cake that Alice eats in Alice's Adventures in Wonderland that makes her grow after having been shrunk by a potion. However, Shigeru Miyamoto later corrected himself, saying that this was a misunderstanding the mushrooms were actually inspired by the concept of mushrooms being associated with magical worlds in general, like the wonderland of Alice's Adventures in Wonderland and the Mushroom Kingdom. 1.1.6 Super Mario Land 2: 6 Golden Coins.1.1.2 Super Mario Bros.: The Lost Levels.Regardless, despite its simple premise, the item has become one of the most iconic items in video game history, and it is almost as well-known as Mario himself.

Mario and sonic at the mushroom world