Obviously it would take far too much time to list every episode title & for you read that list, plus the fact it would have to be updated regularly, so your best bet is to go to either Wikipedia or TVRage and peruse the titles at your leisure.
Moe Sizlack is not in EVERY Simpson's episode, although he is in most.
Raging abe simpson and his grumbling grandson in the curse of the flying hellfish
what about
Too many to enumerate ; you can look to the related link below for yourself and read every episode title .
itunes
Bart the General is fifth episode of The Simpsons.
Episode 3, Season 20.
he did in one episode
Simpson appeared in the Dragnet 1969 episode 3 - "Community Relations." While uncredited, Simpson had one speaking line, but that is not shown on the video at the link. To view a video of a part of that episode, go to the Related Links.
Oh there is lots of Simpson summer episodes. I can name a few. Summer of FT42 aired in May 1996 since every season goes from September or October or November to about May
The episode is Treehouse of Horror XIX (19).
Season 17 Episode 20