Rock, paper and schissors in Alex Kidd was unfair given you had to learn the patterns by blind luck or death.
If I were to reboot Alex Kidd, I would introduce two new martial arts to compliment Alex' Shellcore style. Bladecore and Fancore.
Each core technique is based on rock, paper and scissors and certain enemies and obstacles require the right core technique to deal with them.
As for the card game in mind, that's more lengthy to explain, but the idea is Alex Kidd may visit saloons and sit in games that play this card game for prizes.
So Alex Kidd would have skilltree? Interesting.