Assuming that I can do it 22nd - 24th or a few days after Easter Sunday then I can do:
Sonic 1 - Very likely to be under 30 minutes comfortably
Sonic 2 - About 26:00, pretty much guarantee sub 30 minutes
Sonic Generations - Me and Paraxade are pretty close, my PB is about 1:20, which is what he got at AGDQ and I know I can improve that.
SRB2 (As a backup because I'm probably not the best person available)
Sonic Classic Heroes
EDIT: I can do Sonic Colours (Egg Shuttle) as well because I'm not bad at that game either
EDIT2: I can also do Sonic 1 GG,
and Sonic 2 GG(not as good as FF so she should do it, I can be backup if its that necessary),
Sonic 3D Blast(Mega Drive version) - PB is 38 minutes for SMD version
EDIT3: Sonic Generations mods: I've streamed them in the past so I've no problem with that, I'll keep updating the mods I can do as I practice them more and get more confident with them - I'll do Wave Ocean (Classic And Modern), Rainbow Road (Modern).
EDIT4: Sonic and Mario At The 2012 Olympics - I can play that because I'm pretty good at it, as for goals maybe some people could give me some ideas?...
Note: These are only possible if the dates are as stated above