5.5 Yu-Gi-Oh figures you should never forget exist

One of my favorite pieces from Yu-Gi-Oh, Dark Magician Girl is still quite useful with other Mystical pieces. It all lies in her trait, which allows her to take 2 standard powers from a friendly Mystical piece within 8 squares. If you've got someone fully loaded with powers, by itself and/or from outside sources, or someone that can choose their own powers, those can then be transferred over to her! Additionally, consider her start line: 9-11-18-3 with Sidestep, Pen/Psy, Invulnerability, and PC. That's not quite worth her points, but put with another Mystical piece or two (especially one with Willpower), she can be devastating. Oh, I'll take a Perplex & Pulse Wave, please!

Mystical Elf is a decent enough support piece. With Support & Probability Control, she's pretty comfortable sitting in the back line. It's her Mystical Healing that makes her really special. You just flip a coin every turn to heal an adjacent character for one. For me, Mystical Elf is best used on someone who can carry her around, especially colossals who can shield her with their bulk. Colossals will also usually have an easy time running away so that they can be healed next turn. She makes an impressive little health battery. That last click is a little odd. It makes her a dedicated Support piece with with 19 defense, but only 9 attack. She'll be reasonably hard to hit, but she'll have just as hard a time healing most likely.

Dragon Piper is an absolute sleeper hit. He requires a bit of positioning to play right. No move/attack, no willpower, and at best 18 defense at range (19 if it perplexes itself). For 86 points, it's really got to earn its keep. Well, I'd say it tries really hard to get there using its Dragonic Control. Its LOF can't be hindered, gets to MC 2 targets at 7 range, and whoever it targets gets -3 defense for the turn! It only has to target using its MC, not hit, so this guy can seriously bring down defenses with minimal effort! Just Perplex up his attack so you're more likely to grab victims, bash one with the first, the second can easily bash the first, and then they're all open for whatever you want to do. Nobody will see this thing coming.

Neko Mane King is just the cyoodest widdo kiddy you've ever seen, and your opponent will pay for messing up its fur. This thing is all about its trait, where if your opponent damages it from an attack, his turn basically ends. No actions, not even free ones. That's harsh! It's also got Plasticity to lock your opponent down & Phasing to get it wherever it needs to go. Push it to Super Senses and your opponent's in a world of trouble! Imagine the stupidity of putting this with the Phoenix Force and giving it the Colossus fragment. Now it gets Invulnerability, Super Senses, Plasticity, Outwit/Perplex, and Poison all annoying your opponent really hard! Timing will be a bit of an issue here, as you'll want to rush it up right when your opponent is relatively clear of tokens, or else it won't matter much if they damage it.

There's a lot of power in this little guy. Just by itself, it can go with your squad of bruisers to keep your target locked down and Empower them. It's fairly easy to pop, but once they do, your squad loses tokens. That could be rather inconvenient for his point cost... but there's a sneaky extra use it can have...

Should you lose 90 points worth of characters (it happens), you can KO that Dark character to bring in the Magician of Black Chaos. You're paying 30 points for the potential to bring in a 180 point piece once you've lost a significant amount of material. This guy doesn't quite justify his points; I'd place him more like a 125 point piece now. That's still a major bargain. Starting at 10-11-18-4 with Running Shot, Invulnerability, Outwit, Pen/Psy & Energy Explosions, yeah he's a solid enough threat. If he uses either attack power, you give the hit targets a Chaos token you can use to force a them to reroll their attacks later. If they do bring you down a bit, you're still sitting on Pen/Psy, Impervious, & Probability Control, maybe even a Pulse Wave near the end. Yeah a 9's not great, but combined with a PC/Perplex, it can still be useful.
If you need to, since the Ritual Summon is a free action, you can move Sangan (or Witch of the Black Forest is fine, too) before the sacrifice and you have a fresh character further up on the field. He should be a major comeback factor for you if you're willing to pay 30 points for the privilege.

... or you play a Dark/Yugi team and throw a Thug in there to make MBC a ludicrously cheap 10 points.

Yu-Gi-Oh is generally very weak compared to current figures, or even for its time. I got in just after that was a thing, so I never got to take advantage of the Yu-Gi-Oh scenario's magic & traps. Still, it's got enough unique tricks in there to be worth your consideration.