Sigma-Alpha 2 is a group mentioned in  and Sonic Adventure 2 . It is a team of Sonic Adventure 2: Battle GUN troopers who were responsible for the capture of Sonic the Hedgehog during the Space Colony ARK incident.
Sigma-Alpha 2 was deployed by
GUN to apprehend Sonic when he had been framed for the theft of a Chaos Emerald. Upon locating him, the team introduced themselves to Sonic before handcuffing him and taking onboard their helicopter. While flying above the  capital city however, Sonic managed to take out Sigma-Alpha 2 and escape to the city below.
In other media
The Paladin Team Sigma-Alpha 2.
comic series and its spin-offs published by Sonic the Hedgehog Archie Comics, Sigma-Alpha 2's full name was Paladin Team Sigma-Alpha 2. Like in the games, this group was responsible for capturing Sonic the Hedgehog when he was framed for a theft of a Chaos Emerald. After clearing up the misunderstanding, the group became allies of the Knothole Freedom Fighters, though they would later be legionized and brainwashed into serving the Eggman Empire.
It should be noted that Sigma-Alpha 2 can be shortened to "SA2", which was possibly a self-reference within as the game's abbreviation is also "SA2".
Sonic Adventure 2
Sonic Team (June 23 2001) Sonic Adventure 2. Dreamcast. Sega. Area/Level: Opening sequence (Hero story). " Helicopter pilot: Sigma-Alpha 2 heading due south over the city." ↑
Sonic Team (June 23 2001) Sonic Adventure 2. Dreamcast. Sega. " Sonic the Hedgehog: I'm Sonic! Sonic the Hedgehog! Some military troops suddenly showed up saying they were looking for me. Looks like they might be taking me for a ride somewhere! Hey! What's this? Handcuffs? Wait a minute! What are you talking about? I'm not a deserter from any military facility!"
Main article | Gallery | Beta elements | Staff | Re-releases ( Battle | 2012)
Sonic ( Super Sonic) | Tails | Knuckles | Amy* | Shadow ( Super Shadow) | Rouge | Eggman | Big*^ | Tikal* | Chaos* | Chao ( Dark Chao/ Walker*, Hero Chao, Chao Walker*, Chaos Chao) | Metal Sonic* | Gerald | Maria | President | Secretary | Sigma-Alpha 2 | Animals ( Bat, Bear, Boar, Cheetah, Condor, Dragon, Gorilla, Half Fish, Parrot, Peacock, Penguin, Phoenix, Rabbit, Raccoon, Seal, Sea Otter, Sheep, Skeleton Dog, Skunk, Tiger, Unicorn)
G.U.N troops Blue Eagle | Bomb Beetle | Bomb Wing | Gold Beetle | Gun Beetle | Gun Hawk | Gun Hunter | Gun Wing | Hornet-3 | Hornet-6 | Hornet-9 | Laser Hawk | Laser Hornet | Laser Hunter | Mono Beetle | Phoenix | Rhino Cannon | Rhino Jet | Rhino Metal | Rhino Spike | Shield Hunter | Sky Hawk | Spark Beetle | Spring Beetle
Artificial Chaos ( Artificial Chaos P-1, Artificial Chaos P-100, Cell, Float Type, Guard Type) | Badniks ( Buzz Bomber, Chopper, E-1000, Gola, Unidus, Kiki) | Boo | Boom Boo | Egg Beetle
City Escape** | Wild Canyon** | Prison Lane | Metal Harbor** | Green Forest** | Pumpkin Hill** | Mission Street** | Aquatic Mine | Route 101 | Hidden Base** | Pyramid Cave | Death Chamber | Eternal Engine** | Meteor Herd** | Crazy Gadget | Final Rush** | Iron Gate** | Dry Lagoon** | Sand Ocean** | Radical Highway** | Egg Quarters** | Lost Colony** | Weapons Bed | Security Hall** | White Jungle** | Route 280 | Sky Rail** | Mad Space | Cosmic Wall** | Final Chase** | Cannon's Core | Green Hill
Downtown Race | Grind Race | Planet Quest | Pool Quest | Deck Race | Pyramid Race
Black Market | Central City | Chao Garden ( Dark, Hero, Neutral) | Chao Kindergarten | Chao Stadium | Prison Island | Station Square | Space Colony ARK | Moon
B-3x Hot Shot | Biolizard | Dr. Eggman | Egg Golem | F-6t Big Foot | Finalhazard | King Boom Boo | Knuckles | R-1/A Flying Dog | Rouge | Shadow | Sonic | Tails
Amy Flash* | Black Shield* | Black Wave* | Booming Missile* | Bounce Attack | Captive Light* | Chaos Bind* | Chaos Control | Chaos Impact* | Chaos Screw* | Chaos Spear | Chaos Strike* | Charm Ray* | Crazy Rush* | Crouch | Dark Finish* | Dark Omochao* | Dig | Drill Claw | Drill Drive | Fire Somersault | Glide | Grind Step | Grinding | Hammer Punch* | Heaven's Justice* | Hell Bomber* | Hip Drop* | Hover | Homing Attack | Jump Dash | Kick/Kick Attack | Knuckle Spin* | Laser Missile* | Light Attack | Light Speed Dash | Lock-on | Lock-On Missile | Magic Hands | Omochao | Pick | Power Flash* | Power Laser* | Propeller Punch | Punch (Eggwalker) | Punch/Punch Attack | Rocket Launcher | Rumble Launcher* | Screw Kick | Somersault | Sonic Wind* | Speed Up* | Spin Jump | Spin Dash | Spiral Upper | Storming Heart* | Super Sonic Boost | Swim | Thunder Arrow* | Time Stop* | Volkan Cannon | Wrath of Gaia* | Zap Laser*
Level Up Items Air Necklace | Air Shoes | Ancient Light | Bazooka | Booster | Bounce Bracelet | Flame Ring | Hammer Gloves | Iron Boots | Jet Engine | Large Cannon | Laser Blaster | Light Speed Shoes | Magic Gloves | Mystic Melody | Protective Armor | Shovel Claw | Sunglasses | Treasure Scope
English voice actors
Ryan Drummond ( | Sonic) Connor Bringas ( | Tails) Scott Dreier ( | Knuckles/ GUN Soldiers) Jennifer Douillard ( | Amy Rose) David Humphrey ( | Shadow the Hedgehog) Lani Minella ( | Rouge/ Omochao) Deem Bristow ( | Doctor Eggman) Moriah Angeline ( | Maria Robotnik) Marc Biagi ( | Gerald/ GUN Soldiers) Steve Broadie ( | President) Shelly Fox (Default menu voice) | Jon St. John ( | Big) Elara Distler ( | Tikal) Tomoko Sasaki (
Japanese voice actors
Jun'ichi Kanemaru ( | Sonic) Kazuki Hayashi ( | Tails) Nobutoshi Kanna ( | Knuckles) Taeko Kawata ( | Amy) Kōji Yusa ( | Shadow) Rumi Ochiai ( | Rouge) Chikao Ōtsuka ( | Eggman ) Etsuko Kozakura ( | Omochao) Yuri Shiratori ( | Maria) Kinryū Arimoto ( | President) Shun Yashiro ( | Big) Shelly Fox (Default menu voice) | Tomoko Sasaki (
OST / Vocal Collection / Official / Sampler / 20th Anniversary /
Passion & Pride A Ghost's Pumpkin Soup | Believe In Myself | Deeper | Dive into the Mellow | E.G.G.M.A.N. | Escape from the City | Fly in the Freedom | For True Story | It Doesn't Matter | Kick the Rock! | Live and Learn | My Sweet Passion | Rhythm And Balance | Space Trip Steps | Supporting Me | The Supernatural | Throw It All Away | Unknown from M.E. | Vengeance is Mine
Angel Island | Ancient Ruin | Auto Running | Ball Switch ( Gravity Control Switch, Hourglass, Time Stop Switch) | Bomb | Bungie Vine | Chao Adventure^ | Chao Adventure 2^ | Chao Eggs | Chao in Space | Chao Key | Chao Machine | Chao Transporter^ | Chao World | Chaos Emerald | Chaos Drive | Container ( Cage) | Corkscrew loop | Cyclone | Dash Panel | Dreamcast | Dynamite | Eclipse Cannon | Eggman Bombom | Eggwalker | Emblem | Emerald Radar | Emerald Shard | Fake Emerald | Gerald Robotnik's diary | Goal Ring | Green energy fluid | Grind Rail | GUN Military Truck | High-speed warp tube | Health Gauge | Hi-Speed Shoes | Hint Box | Item Box ( Bomb, Extra Life, Health, Invincibility, Magnetic Barrier, Power Sneakers, Shield, Super Ring) | Kart Race | Key Stone ( Gate Key) | Laser Field Block | Meteorite | Missile | Outfit | Pipe | Project Shadow | Propeller Spring | Pulley | Rank | Ramp | Ring | Rocket | Safe | Shuttle loop | Snowboard | Spinning drum | Swing Bar | Teleporter | Totem Pole | Turtle | Warp Hole | Warp Wall | Weight | Wide Spring | Winding Tunnel
*Appears or is playable only in the 2P mode
**Stage is also playable in 2P mode ^ Dreamcast version of Sonic Adventure 2 only