The Hybrid Warriors is a team created by Erik Hernandez and Gabriela "Gaby" Morales. Basically any friend of Erik's or Gaby's who has joined them in a team fight is considered a Hybrid Warrior. The leaders of this team (besides Erik and Gaby) are Hollow War and Gaby, since they were obviously the first two members. Some other Hybrid Warriors are Noisibush, Technoboy, Nuke Danger and Midown.
The name was Gaby's idea, since Hollow War is basically a hybrid of Hollow Jack and Bio War, Erik liked the name so much that it stayed like that. A little while later, Midown joined the team, and after him came Noisibush and Technoboy. Nuke Danger was the last member to join. They fight in both the Underworld and the WRB, but of course, the fights allow only a maximum of three at a time, so they take turns to fight in fair amounts so no one has more fights than anyone. The Hybrid Warriors are loved everywhere they go, since people feel they represent what a true friendship is. Even the ones who aren't in turn to fight go to see their friends' fights. They are all very close and love each other a lot, they're like a family. Even the ones who join them at least momentarily have their own name, the Hybrid Allies, this is for them to know they might not be as close, but they're definitely not left out. A curious fact about the Hybrid Warriors, is that they change their paint when they fight in the WRB, swapping places between their main color and black. They do this since the black covers most of the assembly this way, giving a message that we're all equal and it's only little things that can tell us apart. They call this the "Hybrid Paint".
The Hybrid Allies are a subdivision of the Hybrid Warriors. These are fighters who are not close enough to the Hybrid Warriors to be considered one of them, but are also not strangers. Some perfect examples are Hadez and Hypernova, who briefly joined Hollow War in an elemental fight in the Elemental Brawl tag team event, a 3v3 event in which only robots in their elemental form could participate. Hadez has not joined again Hollow ever since, but Hypernova did join Gaby a while later, in a team they'd call "Femme Fatales". Another Hybrid Ally is Hypernova's "younger sibling", Ultranova, who like Hadez, joined them briefly and then never again. So theoretically, anyone can be a Hybrid Ally, the only requirement would be to have joined one of the Hybrid Warriors at least once.