Part 1: Factions

Here are some descriptions of the factions in The Gauntlet.

Akuroninja's En4cers

Akuroninja is the leader of this team. Originally, it was a trio of original characters Akuroninja, DSR, and ZyuohCrow. Akuroninja looks like Kuroninja, except he has a red outline on his armour to make himself look more evil. DSR is basically HebitsukaiMetal, and ZyuohCrow is ZyuohEagle, except he's black instead of red and looks more evil than ZyuohEagle. This is an evil faction.

The 6 Squad

This group was formed when Lord Drakkon won the Ultimate Championship and Gokai Silver became the next challenger. Akuroninja's En4cers became Lord Drakkon's backup, so Gokai Silver got the help of AbareKiller, the Go-On Wings, and Kamen Riders KickHopper and PunchHopper. They then became the 6 Squad, with Gokai Silver as the leader, AbareKiller as the enforcer of the group, and the others are for the tag team division and the Mixed Tag Team Division.

Underworld

This group is evil, but it's also a fan favourite faction. Unfortunately, they don't have a lot of achievements. Deathryuger is the leader of this faction, and other members include Kamen Riders Specter and Necrom.

Kyurangers

It's obvious who's on this team, especially if you watched Uchu Sentai Kyuranger. Recently, before this series began here, there has been a falling out with the Kyurangers, with them being divided into 2 sides: Team Lucky, and Team Tsurugi. ChameleonGreen also betrayed the Kyurangers and joined the Underworld Faction for some reason.

Part 2: What happened last episode before "episode 1"

Here's what happened before the 1st episode here.

There's a single elimination tournament to determine a new challenger for the Gauntlet Ultimate Championship at the June 10 Episode.
ShishiRed attacked HououSoldier during an All-Star Championship match against Kuroninja, the All-Star Champion.
Kamen Rider Build is the Rider-Division Champion, and he received a warning from Kamen Rider Evol, who's about to make his debut.
Kamen Rider Cross-Z and Kamen Rider Grease defeated EngineBros and RemoconBros to become the new Tag Team Champions.
ChameleonGreen defeated WashiPink and retained her Women's Championship.
Lord Drakkon challenged the Go-On Wings to a mixed tag team championship match, and lost.
Anti-Kuroninja is returning soon, and he wants the Gauntlet Ultimate Championship.
GokaiSilver is the Ultimate Champion.

Part 3: The Champions (before episode 1)

Ultimate Champion: GokaiSilver
All-Star Champion: Kuroninja
Women's Champion: ChameleonGreen
Tag Team Champions: Kamen Rider Cross-Z and Kamen Rider Grease
Mixed Tag Team Champions: Go-on Wings
Rider Division Champion: Kamen Rider Build