Guitar/keyboard/drum machine :
1/ : Meridian compressor (I would also consider Walrus Deep Six, but I know Meridian would be my final choice)
1.9/ : Modded BD-2 as OD/Distortion, on perfboard if possible. * If it was only one effect allowed, it would be this one *.
2/ : Fuzz Factory from Zvex (a real original one please) and a simple noise gate if we need to cut the whistling noise on some settings.
2.1/ : Dandy Horse or Flintlock for modulation (* or one of these...)
2.2/ : EHX Oceans 11 reverb (this thing can't really get cloned, the chip inside is much more powerful than FV-1, and "it's a good chip", see replies #21, 22)
Reverb build question - Page 2
www.diystompboxes.com
3/ : Echo-DC, it's a Memory Man early version, called Echo 600. Hydra is tempting, but we'd have many regrets, except for the drum machine.
4/: Boss GE-7 EQ, without any mod.
5/ : Boss RC-3 Loop Station (* or this one...)
Bass :
Meridian
Bass Amuser, bass tube overdrive (can also work on guitars. If the guitar player isn't satisfied, he can always mod it, right ?)
360 Bass Fuzz or big muff op-amp
CE-2b with intensity + vibrato mods, or Redshift Phaser (EHX Small Stone with every mods), or a Flintlock.
TS-50 preamp
EHX Oceans 11
RC-3 loop station
Pro-Cessor mixer blender splittter, so we can play a bit with the guitar effects, without bothering with difficult-to-design, time-consuming and sophisticated heavy mods.
I would add the Spectron enveloppe filter for all instruments, but you said only 5.... I guess I'd try to smuggle it under my jacket, next to a BBW, an OCD v.2 hidden in my pants, and a Tweed Man Overdrive under my hat.