Brief thoughts -
I was a kid that was brought up playing pokemon and notably pokemon stadium I must have sunk close to 1000hrs+ into that game
One merit of that game I believe was choosing the moves a pokemon could do..
Would it be a good suggestion during arena battles where each Illuvial has potentially 3 different omegas that you can choose from - allowing for more dynamic play during the game and the ability to react to particular teams / synergies of both your own team and your opponent.
For example- Ramphyre has 3 omegas -his AOE, his single target high crit slash with a bleed, and then a fire cone shooting fire in a single line direction on the board.
You could choose the omega to use for the next turn during the intermission or alternatively integrate the omegas into levelling the illuvial or NFTs as training guides, these training guides could be bought or found in overworks and further add to the development of illuvials while also creating a specialisation of sorts
From a dev point of view it shouldn’t be too hard other then integrate the omegas as actions and build the cards/tokens for new abilities.