heh :P I support the idea of RedXVI being a hidden boss.
get all 7 emerealds, and annoy him once in each location (and put one per zone, with the Exception of GFZ, since he already has 2 there)
:P I can see it now...
*cutscene*: And so sonic and his friends defeated eggman once again! peace i- *THUNDER SOUND* *sonic and co look behind them...and then look freaked out.*
GIANT LOOKING REDXVI: You jumped on my house, ruined my picnic, peed in my pool, locked me in a random room in an underwater ruin, PUSHED MY FRIDE OUT OF MY APPARTMENT WINDOW, and NOW you blow up the meteor I was planning to retire on! YOU CAN ALL DIE NOW! *cue boss fight*
:P ...I like that mental image. XD
and if he ISNT a secret boss, at least make more places where we can annoy him. XD