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Sonic News Network
Sonic News Network

E-121 Phi (E-121 ファイ E-121 Fai?), also spelled E-121 “Φ”, is the name of an E-Series robot model built by Dr. Eggman based on Emerl. Dr. Eggman took the Gizoid's data and copied it to create the Phis. They are mass-produced, though only fourteen are seen. The Phi robots are powered by Chaos Emerald Shards, rather than whole Chaos Emeralds.

Abilities and differences from Emerl

The only physical difference between the Phi robots and Emerl is Phi's gray hue and brown eyes, as opposed to Emerl's orange and blue. The Phis' abilities are stated to be similar to Emerl's, however, the Phis only use a complete moveset of one of the playable characters, making the Phis robotic, gray-scale versions of the playable characters. The majority of the Phi robots appear to be of the same intelligence level as Emerl when he had only absorbed two Emeralds, however, the last two Phi models the player encounters, #13 and #14, had greater speech capabilities.



Rouge confronting Phi #1.

The first Phi model created by Dr. Eggman, it is fought in Rouge's episode at Battle Highway in Central City. Eggman attempts to use this Phi to defeat Rouge, however, Rouge effortlessly defeats the Phi and claims the robot's Emerald Shard as her own. Unlike later models of the Phi, #1 uses basic attacks used by Emerl after first establishing a Link with Sonic.


Sonic confronting Phi #2.

Like the first model of Phi, this one uses basic attacks used by Emerl at the start of the game. This Phi is first fought by Sonic outside of Tails' Lab in Emerald Town and is later fought by Emerl after he receives training. This is the first Phi fought in the game, as well as the first enemy Emerl fights on his own. After it's defeated by Emerl, it runs away, presumably to Gimme Shelter.

Phi #2 is later fought again in Night Babylon at Club "Rouge" alongside #3 in Knuckles' episode, unlike the first encounter with the robot, it now uses Rouge's moveset. #2 is then completely destroyed by Knuckles and Emerl, leaving an Emerald shard behind.


Phi #3 is fought in Knuckles' episode in Night Babylon at Club "Rouge" alongside #2. The two Phis are fought by Knuckles and Emerl, #3 uses Knuckles' moveset. Once #3 is defeated, it leaves behind an Emerald shard.


Phi #4 is fought in Knuckles' episode at Emerald Beach. After Knuckles trains Emerl with a one K.O. battle, Dr. Eggman arrived to take Emerl back by force. The two then quickly dispose of the mock Gizoid, obtaining another Emerald shard in the process. Phi #4 uses Tails' moveset.


Phi #5 is the last Phi robot to be encountered in Knuckles' episode. The player encounters the robot after pursuing Eggman to the Crossing in Central City. The Phi uses Shadow's moveset and is fought like the previous three Phi models by Knuckles and Emerl. As with all Phi model robots, Phi #5 releases an Emerald shard upon defeat, which supplied the two with enough shards to recreate a Chaos Emerald.


Phi #6 is fought in Amy's episode on Emerald Beach . After Emerl wondered off, he discovered the robot and attempted to fight it, however, Amy arrived and scolded Emerl for running off and being rude to the robot, Amy then attacked the Phi for attempting to attack Emerl. Amy and Emerl then fought #6 alongside #7. Like Phi #3, #6 uses Knuckles' moveset. After Phi #6 is defeated, Amy and Emerl obtain another Emerald shard, which prompts Amy to train Emerl in order to defeat more Phis and obtain more shards so that Sonic will respect her.


Phi #7 is fought in Amy's episode alongside #6 on Emerald Beach. The Phi model is fought by Amy and Emerl and uses Chaos Gamma's moveset. After Amy and Emerl defeated Phi #7, it leaves behind another Emerald shard.


Phi #8 is fought in Amy's episode at the Signboard in Night Babylon. It is fought alongside Phi #9 against Amy and Emerl. Like Phi #5, it uses Shadow's moveset. After it was defeated, Phi #8 left an Emerald shard which, along with #9's shard brought Amy and Emerl's shard count up to four.


Phi #9 is fought alongside #8 in Amy's episode. It is fought in Night Babylon and uses Amy's move set in battle. Once defeated, it releases another Emerald shard for Emerl.


Phi #10 does not appear in any of the game's episodes and the model numbers skip straight to #11 at the start of Cream's episode. Although the fate of #10 is never revealed, at some point between Amy's and Knuckles' episodes, Rouge obtains another Emerald shard, suggesting that Rouge may have the defeated the tenth model.


Phi #11 is fought in Cream's episode at the Laboratory in Gimme Shelter. #11 is fought alongside #12 against Emerl and Cream (although Cream does not participate in the fight). #11 uses Sonic's moveset and, as with all of the Phi models, released an Emerald shard upon defeat, Emerl then gave the shard to Cream to hold as she found the shards pretty.


Phi #12 is fought alongside #11 in Cream's episode in Gimme Shelter. Like #4, #12 uses Tails' moveset in battle. Once defeated, the robot released an Emerald shard which was given to Cream.


Phi #13 is fought in Cream's episode at the workshop in Gimme Shelter. Phi #13 is fought alongside #14 and is fought by Emerl and Cream however, as with the previous battle, Cream does not fight back and isn't present at all during the second fight. As with #2, #13 uses Rouge's moveset, and once defeated, it released another Emerald shard. Unlike previous Phi models, this model, along with #14, is capable of fluent speech and cognitive thought, as opposed to previous models, which used speech similar to Emerl when had only absorbed two Chaos Emeralds.


Phi #14 is Eggman's last model in the Phi series, and therefore, is the last Phi robot encountered during the story mode. It is fought in Cream's episode along with #13 and fought against Emerl and Cream, although Cream does not fight and is not present during the second fight. As with #2 and #13, this model uses Rouge's moveset and it was defeated. It left behind the final Emerald shard in possession of the Phi robots.


  • Phi is the twenty-first letter of the Greek alphabet. However, since the first E-100 Series robot was designated E-100 (as in the Greek alphabet, Alpha is counted as zero, then Beta is counted as one and so on), the Phi robots should be designated E-120, and E-121 should be Chi. This error was acknowledged by Ian Flynn in the Sonic Universe blog, where Phi and Chi are listed by what their model numbers should be with the error noted in Gamma's logs.
  • Phi has a lower serial number than E-123 Omega, meaning that it was created earlier. However, Sonic Battle takes place after Omega's first appearance (in Sonic Heroes), as Rouge comments on Gamma and Omega looking similar. This might mean that Eggman was working on Phi before Omega, but he finished building Omega first. Eggman may also have saved the Phi model robots for a later purpose, such as collecting Emerl.
  • Rouge's moveset is the one most frequently used by the Phi models, as it is used by three separate models during story-specific events.
  • Phis are never encountered in Holy Summit.
  • The theme of the Phis, which is also Emerl's theme and the music for the Colosseum arena, was remixed as the music for Nonaggression in Sonic Advance 3.




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