This is MY OPINION(THIS IS FOR ARENA, FOR SOME REASON IT SAYS INSANE)
5: Red Knight
Red Knight is an all around quite good character, mainly because of his irritating RT+Y, because if you can consistantly lock people in it, they will die. Only number 5 though because Rammy is quite popular in arena, and that counters it.
4: Blue Knight
Blue Knight is a solid character, for his ability to freeze people then begin juggling. He is alsy useful to get out of situations where he would have died if he was not blue knight. His main counter is Yeti, but not very many people use it in arena as of my knowledge.
These two can jam you into a wall, the only problem is that its hard to pull off and other than that, these characters are outclassed by the above two.
Also possibly the most popular characters, these have amazing magic, being able to knock you back constantly if they are good. The magic does high damage, and the characters in general are great.
1: Orange Knight
The orange knight in my opinion is the best arena character in the game, because out of all RT+Y, his goes the farthest, so if you are good with magic AND juggling, you can dominate quite easily.