Oh! Edo Rocket is a pretty recent anime, so I hope I haven't butchered the tags or anything, because it currently appears that there are no other images with the tag oh!_edo_rocket.
As far as I can tell 溶けレカ is referring to Eureka in latter episodes when she has short messy hair and scars/lesions on her skin. MeltReka seems good.
Also, I'm guessing the 'Eureka' on the far left is in fact Anemone, mainly based on the unidentified animal she's holding. The Cast section doesn't agree though.
Well, the leftmost Eureka has true Coralian eyes, so it's unlikely to be Anemone. Of course, Anemone's hair color is also different, but that's easy enough to fix, unlike the aforementioned issue.
「溶けレカ」 refers to the middle part of the plot of Eureka Seven (around episode 25), when Eureka is almost absorbed by the Coralians and starts looking melted. With very short hair and scars on her forehead, that look. So that's called 溶けてるエウレカ [melting Eureka], and abbreviated it's 「溶けレカ」.
So it looks like "Meltreka" is indeed mostly correct. :) To be honest, I forgot why Eureka looked like that in the first place, so after being reminded of that, this seems not so mysterious after all...
Apparently, since the outfits being worn by Eureka and Renton in that image never appeared in the series.
Lolireka: EurekaEureka: Osora-sanMeltreka: LeeronYou [Leeron] have your own [Gurren Lagann] movie, isn't that good enough!?OK, I'll be Meltreka~♥Well then, I'll be young Eureka!