Make sure to give any advice you can to the other players, tho dont do so when they may be a bit salty , and dont overload them with stuff also.
You can also try running danisens. Basically you have everyone do friendlies but have a ranking system to it. Everyone starts off at 0, and if you win you get a point, if you lose you drop a point, unless your at 0. Keep having them play until you start seeing a good enough gap, then you can use that to group the players of simillar skill levels together , so people dont feel discouraged when playing people much better than them and just getting destroyed the entire time. If you already have a good idea of skill groups then just start them off like that and have like 10 or 15 point differences between them as a starting point. Of course when doing this make sure all the people in a group are switching between whos playing who a lot to get the best results, also makes it more fun when your switching it up who your playin against at least semi often. You can google about them to find out more specifics probably.
Ask each person if they know some high/top level players of their char, watching vids of those players could inspire them to work harder or try out new things they didnt think of before watching that player.
If people seem real lost on what to do in a matchup or just with their char see if theyd like to talk over some strategies or test stuff out in training mode to see if you guys can find something to help out in the matchup, such as how to beat a specific move or ways around different setups. Or practice SDIing things like falcos Dthrow>Dair so your not spiked offstage, out of certain multihit moves like Pikas Dsmash or marths side B rapid stab ender, Robs Dsmash etc.