E-121 Phi

E-121 Phi (φ) (ファイ Fai) is an Emerl-based robot made by Doctor Eggman. Dr. Eggman took Emerl's data and copied it as stated in Rouge's story mode. The Phi robots are powered by Chaos Emerald Shards, rather than whole Chaos Emeralds.

The only physical difference between Phi and Emerl is Phi's grey hue and brown eyes, as opposed to Emerl's yellow and blue. The Phi's ability to copy attacks is identical to that of Emerl, but since the ability is only powered by Chaos Emerald Shards, as a whole it is weaker than Emerl's. At first they don't have much vocabulary, repeating one word while speaking, such as "Located! Located!" But later, they're able to speak more fluently, such as "Captured! I will capture you! I will capture you for Dr. Eggman!"

Trivia

 * Phi is the twenty-first letter of the Greek alphabet. However, since the first E-100 Series robot was designated E-100 (rather than E-101), the Phi robots should be designated E-120. E-121 should be Chi, and E-122 should be Psi.


 * Phi has a lower serial number than E-123 Omega, suggesting that it was created earlier. However, Sonic Battle takes place after Omega's earliest appearances (in Sonic Heroes and Shadow the Hedgehog), as Rouge comments on Gamma and Omega looking similar. It is unclear why Eggman didn't use Phi until Sonic Battle.