If you could change one type matchup on the chart, what would it be?

I suppose I could have phrased that better(writing has never been my strongest trait). I meant adding a Resistance to Water for Ice types. Ice types resist only themselves from a defensive standpoint so not only would they be Super Effective against Water on offense, but they would also resist Water defensively. Water types resist their own typing and given that Ice is effectively frozen Water, it makes sense for that to carry over. Plus freezing Water should be just as "effective" from an Offensive standpoint as shocking them with Electric attacks. Only reason Grass is effective against Water is due to the Rock/Paper/Scissors with respect to regional starters(and that Plants absorb Water).

See my above post for answer on Water + Ice but I wanted to add that Tatsurgiri is already vulnerable to Ice via Freeze Dry. Lots of Ice Types learn it, including my Arctic Fox. Making the type change would make other Ice moves like Ice Beam or Blizzard follow suit so to give Freeze Dry some relevancy, I’d guarantee Freezing opposing Water Types unless they’re also part Ice. Otherwise, Ice Beam and Blizzard will simply outclass it on raw power if Ice became super effective on Water types.

The only Water attack that would make sense to deal x2 Damage on Ice types would be Scald. Outside of that, neutral damage at best(if not resisted as I’m proposing). Offensively, Ice is rock solid and making it useful against Water would likely make it the best Offensive type in the game. Defensively though, Ice is putrid and that is why I’d make it resist Water attacks.

Another thought I had was for Psychic to resist Fairy or have Psychic deal x2 against it to create a new triangle of Dark/Psychic/Fairy.