It is possible that meta-emulation may have been used. I remember reading something on the site of the former Digital Eclipse that mentioned a lot of it in their past works. That could be one theory.
For Ghosts 'n Goblins, take a look at the Amiga 500 version. I'd say that was THE closest home port we got (despite not being on an actual "console", which I know is what the discussion is).
I would argue that the releases on the PS1/Saturn on the Capcom Generations Collection discs were honestly emulations. Playing SF Collection 2 on the PS1, something definitely didn't feel "ported" about SF2/CE/Turbo at all.
Not so much as the different flavors (though I've heard issues with HTC Sense and Samsung TouchWiz having incomplete bluetooth drivers), but the various game controllers one can get for smartphones/tablets all work in different ways.
courderoy guy: how would the numerous types of controllers that can work for Android in their own ways be addressed? This might be a concern, as some game releases from others have little or no support (in terms of emulated arcade games and how they work).
Same here. Would be nice to test out how the games work with the various methods of using hardware controls. Hopefully it should be far better than the "xperia play" functionality of R-Type.