Guest: Hard to know what you're driving at but I'll weigh in. Assuming you're not having us all on, the chords you would use for a simple "three-chord" song (such as a blues, or When The Saints Go Marching In, and a million others) in E flat would be E flat, A flat and B flat seven. If you're playing jazz, standards etc then the chord sequences of the tunes you have in mind very likely extend beyond that. You just have to find out the chords sequence for each piece in advance. Chords are chords, a pianist will use the same name for chords as a guitarist. Ask the pianist what they are for each piece and write them down or learn them piece by piece. Just chiming in without preparation and playing the "right chords" in such cases is a difficult skill to acquire- no answer on this forum or any other will magically enable you to do get near it. I may be miles off the mark but hope this helps. Good luck.