Early Electronic included David Palmer (ABC, The The) on drums and Denise Johnson (Primal Scream) on backing vocals. Dunno if Palmer performed live with them but he was definitely on the Getting Away With It single. Neil Tennant and Chris Lowe obviously guested too and were present at the 1990 LA Dodgers stadium shows in support of Depeche Mode. Johnson can be seen in the live band that performed Out Of My League & Second Nature on Later... with Jools Holland in 1996.
Later period Electronic featured Jimi Goodwin (Sub Sub, Doves) on bass/backing vocals and Ged Lynch (Black Grape, Peter Gabriel) on drums. Phil Cunningham first appeared during TV appearances to promote Twisted Tenderness as second guitarist; I remember him on Jo Whiley's C4 TV show performing Haze.
Monaco around the time of the albums aside from the obvious included Paul Kehoe (our very own Old Lead Foot) drumming and Andy Poole on keyboards. For gigging they had a second guitarist (name escapes me) and second bassist (ditto) to step in when Hooky sang. By the time of the charity gigs in 2006-07 Andy P, second guitarist & bassist had gone, Hooky's son Jack was helping out on bass and there was a new keyboardist. Not sure of her name.
Revenge had a bit more of a revolving door policy
er, may take me a while to remember who was in and when... I do know when Hooky re-recorded those two unreleased tracks (Televive & The Wilding) for the 2004 Revenge anthology he got Phil Cunningham to play guitar in the studio.