https://www.romhacking.net/hacks/4434/

"Combined PSI" version makes the PSI movesets of Claus and Kumatora similar to those of Paula and Poo from the previous game Earthbound. What that means is, both Claus and Kumatora learn a fair amount of both offensive AND defensive PSI, which radically changes up how you can play the game and strategize. For example, both Claus and Kumatora now learn PK Freeze (Claus only learns up to Gamma level) and can use it in fights, and Claus has only Psychic Shields/Counters he can cast, and Kumatora has only Physical Shields/Counters she can cast.