Judai's cards that are actually good.

The cards Judai used in the anime, in most cases, were very situational, like Edge Hammer, Clay Charge and Burst Return. But he had some awesome cards, and 2 of them are limited and 1 is semi-limited in the current banlist. They are Card Trooper, Necro Gardna and Dandylion. Each of these had their moment of glory, and we'll look at each one now:

Card Trooper

Machine/Effect

EARTH/3*/ATK 400 DEF 400

Once per turn, you can send the top 3 cards of your Deck to the Graveyard to have this card gain 500 ATK for each card sent, until the End Phase. When this card on the field is destroyed and sent to the Graveyard, draw1 card.

This card is a Machine with less than 500 ATK. So, it's a target for Machine Duplication. And the other uses this card has are just as good. It mills the deck, gains ATK and makes you draw when it dies. Pretty good, IMO. But if you want more, you can have it: it's a Debris Dragon target. Simply awesome.

Necro Gardna

Warrior/Effect

DARK/3*/ATK 600 DEF 1300

You can remove this card from play from your Graveyard to negate 1 attack this turn from a monster your opponent controls.

Back when this was unlimited, Twilight decks ruled supreme. You can negate any attack just by removing it from your graveyard. In Twilight, it was easy to dump it through the mill Lightsworns have. Plus, it's a DARK monster, so it boasts all goodies from their support.

Dandylion

Plant/Effect

EARTH/3*/ATK 300 DEF 300

When this card is sent to the Graveyard, Special Summon 2 "Fluffy Tokens" (Plant-Type/WIND/1*/ATK 0 DEF 0) in Defense Position. These Tokens cannot be Tributed for a Tribute Summon on the turn they are Special Summoned.

Great card is great. If it goes to the grave in ANY WAY, you get 2 tokens. With Synchros, this card became broken. Mainly in it's combo in it's own deck, Dandywarrior. Dump it for Quickdraw, get 2 tokens, sync for a Drill Warrior, Summon Debris Dragon, get Dandy, sync for Stardust, get 2 more tokens, revive Glow-up, sync for Formula, draw 1 card, believe in Nexus. Last format, this card was semi-limited, which made this deck quite consistent. This card is also useful for Monarchs. Plus, it can be used as a defense of 3 monsters, all-in-one. Resuming, it's the best card Judai ever played.

As much as Judai's cards were situational, he had some gems that actually see a lot of play nowadays.