A list of relevant combatants during Death Battle Season 8.

King Olly: He's from the 2020 video game Paper Mario: The Origami King.

Miles "Tails" Prower: 2021 marks Sonic's 30th anniversary.

Tempest Shadow: Featured in the MLP comics, especially FiM Season 10.

Trixie Lulamoon: Prominently featured in the MLP Gameloft game where she has both an Alicorn counterpart and her famous Babysitter outfit (the latter spawned a huge chunk of her 2020 fan art).

Starlight Glimmer: As of 2016, she's become inseparable from Trixie.

Spawn: His film reboot was announced in 2020.

Kamen Riders (represented by Saber): Kamen Rider Saber is the 2020-2021 season of Kamen Rider.

Jewelpets (Ruby, Garnet, Sapphie, Diana, Dian, Opal, and Luea): The anime Jewelpet was meant to continue in 2020 with the half-hour theatrical short Jewelpet Attack Travel, but got delayed due to COVID-19.

Gatomon: Digimon has a 2020 reboot and its last matchup was back in Season 4.

Rarity: Is one of Pony Life's main characters.

Doom Slayer: Doom Eternal.

Sir Arthur: Ghosts n Goblins Resurrection comes out in 2021.

Babysitter Trixie vector: https://www.deviantart.com/magnusmagnum/art/Babysitter-Trixie-848021917
Starlight vector: https://www.deviantart.com/jhayarr23/art/MLP-Vector-Starlight-Glimmer-16-818018252