I'm not gunna lie, I find this Combat System simply adequate, at best.
There's not a problem with a simple combat system at all, but there is a problem with a simple combat system that isn't very fun.
Your Combat itself is very boring, with little animation or movement whatsoever, and your Encounter System is a generic pre-determined step based encounter system.
For the Encounter System, I'd recommend doing something along the lines of every time the player moves, the computer creates a number between 1 and 10, and depending on the zone, the acceptable numbers change, for instance, in a zone where there's not a lot of encounters/difficulty, make it anywhere from 3 and lower, to just 1, and if it's a high zone, maybe 6 or 7.
I also don't like how Frogger only has Siphon as a damaging move, and how the bees can apparently heal every turn without needing any Mana.
Try making the combat a bit more fun, whether it's fun looking or fun feeling, and it should be significantly better overall. When I tested this, my first thought was oh great, this game feels like a grind fest already. That's not a very good first thought honestly.