They're practically a female version of Sonic and Tails, well except for Blaze being so serious and Marine being a jabbermouth XD.
Called it "Sol Duo" cause they both hail from the other world paralle to Mobius (called the Sol Dimension sometimes in the comics). People tend to forget that Marine can use a special power seen at the end of Rush Adventure. She's most likely hydrokinetic do to her large affliction with water and her name is "Marine".
Anyway, these two are perfect teamates.