This is a very fun game. I have a few recommendations that vary in implementation difficulty:
1. Add another speed multiplier. The game is a little too grindy imo. Maybe unlock after getting a pokemon level 50 since the game really starts to slow down in terms of progress.
2. Have achievements give additional rewards besides life. Maybe have them give a 1% attributes for either power, crit, range, recharge, etc. Or they can be larger buffs, but only a few can be equipped at a time but may be specific to mountain or grass type pokemon to give more agency in conquering levels.
3. Add an additional save and load slot. This makes it easier to switch from healing, invisible, armor shred, etc loadouts
4. Give small leeway to pokemon placement. This will buff cross and x attack pokemon so they are better aligned, making them hit more consistently.
5. Add a discord to make suggestions, point out bugs and add community engagement with meta progression help.