Mateo
Mateo is a tall male humanoid robot with light skin. Mateo can shoot purple plasma shots out of one of his arm cannons, but at a very fast rate of fire. Mateo's purple plasma shots are smaller than Eric's pink plasma shots. Unlike Eric's plasma shots, Mateo's plasma shots cannot travel through some things that would normally stop projectiles (some examples include solid platforms, or spikes) (without damaging some things that would normally stop projectiles (some examples include solid platforms, or spikes)), which stop Mateo's plasma shots and don't stop Eric's plasma shots. Mateo's plasma shots can still hit enemies, bosses, or wooden crates (whilst damaging enemies, bosses, or wooden crates), which stop Mateo's plasma shots. Mateo can also shoot a purple laser out of one of his arm cannons that travels very fast, but he needs secondary fire ammo (which can be regenerated by collecting light-green stars in "Eric & Yannik X", and in "Eric & Yannik 5", secondary fire ammo gradually regenerates on its own, no light-green stars required) to shoot said laser. Mateo has low offense and mobility. Mateo is flightless.
In "Eric & Yannik 5" (after "Eric & Yannik 5" got updated to version 2.0.0), Mateo has white forearms with white hands (Mateo's white forearms with white hands can turn into white arm cannons), Mateo wears a purple bandana with white dots, goggles with dark-blue lenses and dark-blue straps and white rims, a purple polo neck with rolled up sleeves, dark-blue bib-overalls with a purple belt with a white wrench, and purple boots with white laces, and Mateo has average defense, but unlike other playable characters, Mateo carries a purple ballistic shield in one of his hands that protects him from green slimes and small plasma shots. Mateo is also resistant to corrosions caused by green slimes and Mateo's secondary fire ammo regenerates faster.
In "Eric & Yannik X" and "Eric & Yannik 5" (before "Eric & Yannik 5" got updated to version 2.0.0), Mateo has purple hair and purple forearms with white hands (Mateo's purple forearms with white hands can turn into purple arm cannons), and Mateo is implied to have blue eyes, Mateo wears goggles with blue lenses and blue straps and white rims, a purple sleeveless polo neck, purple pants with a blue belt, and purple shoes with white socks, and Mateo has high defense.