It seems that the actual requirement for this achievement is to have played through every level with a character and then defeat the Evil Wizard in the Final Battle level. So if you copy your save file over and you have a character who has played through every level already, you'll just have to play the Final Battle level and defeat the Evil Wizard. If you are starting from scratch, you'll have to play through the entire game on your way to beating the Evil Wizard because piggybacking with a friend to the Final Battle level won't be sufficient.
Red knight and blue knight/eskimo are crowd control characters. Orange knight is great for nailing fire with a reach and can cripple the corn boss if your out of his reach and spam magic. Any character can spam agility and arrows, strength, level 50 drill, or full magic x,x,x,y combo. Castle Crashers Remastered Character Tier List.
I'M GOING TO MAKE ONE THING CLEAR: BARBARIAN, BLACKSMITH, AND NECROMANCER HAVE NOT BEEN BUFFED, AND INDUSTRIALIST HAS NOT BEEN NERFED. IF YOU KNOW SOMEONE WHO STILL BELIEVES THIS, LET THEM KNOW THEY'RE FULL OF ♥♥♥♥.If this guide gets enough attention, then I'll edit it to look similar to my tier list on wikia to the best of my ability, so spread this guide around!On a side note, some idiot staff member on the wiki saw my last few edits to the page as vandalism even though they weren't, and he reverted said edits. As proof of my getting permissin to creat the guide, I will quote my chat with Proffesor Coke here:Aichmomancer: I want to make a tier list for characters.Aichmomancer: But You've already made one.Aichmomancer: So I was wondering if you'd maybe add me as a contributor to your tier list since you're no longer updating it.Aichmomancer: Or should I just make my own, with your permission?Proffesor Coke: You can make your own.Detailed descriptions will be added later.' READ THE DISCLAIMER!' Luffy (None Piece)For credibility on how valid my ranks of the characters are, I've beaten the game with every character, and I've beaten insane mode with the following characters in order of completion1) Orange Knight2) Fencer3) Royal Guard4) Ninja5) Fire Demon6) Iceskimo7) Peasant8) Red Knight9) Brute10) Industrialist11) Bear12) Pink Knight13) Snakey14) Barbarian15) Killer Beekeeper16) Thief17) Conehead18) Blue Knight19) Gray Knight20) Skeleton21) Alien22) Necromancer23) Cultist24) Civilian25) Blacksmith26) Hatty Hattington.