So first of all, I think you should install what meveric calls the "bad" cores on your OGST, it's an extra set of cores available on his repository, they are supposed to be less efficient or to have problems, but I use some of them, especially for the arcade games.
To install them, if I remember correctly, you have to type:apt-get install retroarch-cores-bad
Here are the paths to all the cores (good and bad):\usr\local\share\retroarch\cores\good
\usr\local\share\retroarch\cores\bad
Now, here is the core list and the systems they emulate:3dengine (?)
4do (3DO)
81 (Sinclair - ZX 81)
2048 (Probably a puzzle game)
bluemsx (Microsoft - MSX|Microsoft - MSX2)
bnes (NES / Famicom)
bsnes_cplusplus98_accuracy (NES, SNES, GB, GBC and GBA)
cap32 (Amstrad CPC 8bit)
catsfc (SNES)
desmume (Nintendo DS)
dinothawr (Game)
dosbox (Microsoft DOS)
easyrpg (Game)
fb_alpha_cps1 (CP System I)
fb_alpha_cps2 (CP System II)
fb_alpha_neo (Neo Geo)
fba (FBA-Next v0.2.97.30 -> 0.154)
fbalpha2012_cps1 (CP System I)
fbalpha2012_cps2 (CP System II)
fbalpha2012 (v0.2.97.30 -> 0.154)
fbalpha2012_neogeo (Neo Geo)
fbalpha (FBA-Next v0.2.97.38 -> 0.167?)
fceumm (NES / Famicom)
ffmpeg (Record gameplay)
fmsx (Microsoft - MSX|Microsoft - MSX2)
fuse (Spectrum)
gambatte (GB and GBC)
genesis_plus_gx (Sega MS/GG/MD/CD)
glupen64 (Nintendo 64)
gme (Game Music Emu)
gpsp (Gambe Boy Advance)
gw (Game & Watch)
handy (Atari Lynx)
hatari (Atari ST/STE/TT/Falcon)
lutro (open source games / Create your own game)
mame_0151 (0.151)
mame_0152 (0.152)
mame2000 (0.37b5)
mame2003 (0.78)
mame2010 (0.139)
mame2014 (0.159)
mame (0.166)
mednafen_gba (Game Boy Advance)
mednafen_lynx (Atari Lynx)
mednafen_ngp (Neo Geo Pocket/Color)
mednafen_pce_fast (PC Engine/PCE-CD)
mednafen_pcfx (NEC - PC-FX)
mednafen_psx (PSX)
mednafen_snes (SNES / Super Famicom)
mednafen_supergrafx (PC Engine SuperGrafx)
mednafen_vb (Nintendo - Virtual Boy)
mednafen_wswan (Bandai - WonderSwan|Bandai - WonderSwan Color)
meteor (Game Boy Advance)
mgba (Game Boy Advance)
mupen64plus (N64)
nestopia (NES / Famicom)
nxengine (Cave Story game engine)
o2em (Magnavox - Odyssey2)
pcsx1 (PSX)
pcsx_rearmed (PSX)
picodrive (Sega MS/MD/CD/32X)
pocketsnes (SNES / Super Famicom !!! None Listed !!!)
ppsspp (PSP)
prboom (DOOM game engine)
prosystem (Atari 7800)
psp1 (PSP)
puae (amiga core)
quicknes (NES / Famicom)
scummvm (Game engine)
snes9x2002 (SNES / Super Famicom)
snes9x2005 (SNES / Super Famicom)
snes9x2010 (SNES / Super Famicom)
snes9x (SNES / Super Famicom - Most recent)
snes9x_next (SNES / Super Famicom - Different emulator I guess)
stella (Atari 2600)
tgbdual (GB and GBC)
tyrquake (Quake game engine)
vba_next (Game Boy Advance)
vbam (Game Boy Advance)
vecx (GCE - Vectrex)
virtualjaguar (Atari Virtual Jaguar)
yabause (Sega - Saturn)
You won't find some of these cores in your image since they have been installed separately. Meveric gave them to me for testing purpose, I don't find them anymore on his repository, so I guess he removed them and wants to prepare a clean package with them... I guess they will be available soon. However, while these new cores were supposed to significantly increase the performances, I actually didn't notice any improvement at all! Which is very weird, but maybe it's because of my settings, I need to investigate a little more.
You can also check out these pages, it helps sometimes:https://github.com/retropie/retropie-setup/wikihttp://wiki.libretro.com/index.php?title=Main_Page