Disneyland character meals can be more fun than WDW because there is not necessarily a set group of characters. We love that you never know who you might meet. Our favorite is Minnie's breakfast. We have never seen less than 7 characters there and one time we saw 12. There are a few characters that you typically see there, but they are not guaranteed. We have seen the Fairy Godmother, Captain Hook, and Minnie every time we have been there. Most times we have also seen Max, either Chip or Dale, either Eeyore or Pooh or Tigger (or more than one), and Rafiki. There is almost always a surprise or two. We have seen Tweedle Dum, the Penguin from Mary Poppins, Pinnochio, Sleeping Beauty, Brer Fox, the Mad Hatter and Alice, and probably a few others I am not remembering. That could change at any time though. Goofy's used to be the same way. We typically saw 7 characters there and it was a mix, but sometime in the last few months they totally standardized it just like at WDW meal, and now it is Goofy, Pluto, Minnie, Chip and Dale. We are very disappointed about that and will be skipping it on our next trip.
Ariel's is all princesses. It will almost always be Ariel out front for a photo. You will see 4 Princesses at your table, and there can be some variation in the Princesses. We have seen Cinderella and Belle every time we have been there. Oh- and that rumor that the reason you never see Belle in her gold dress at a WDW character meal is because the dress won't work is false. Belle is always in her gold dress at Ariel's Grotto. As far as for the other two princesses, we have seen Snow White, Tiana, Mulan, Pochahontas and Sleeping Beauty. Based on our experience, Snow White and Tiana are the most common. We were told that Pochahontas was very rare and we were lucky to have seen her the day she appeared.