You can actually use a different combat system along with this plugin as it doesn't modify a lot of default RPG Maker features but rather adding new. If you find any incompatible you can always send me a message and I'll do compatible adjustment.
Viewing post in [ANSWERED] Switching Battle plugins midgame
Thanks Sang! Thanks for making this system, it will lead to some fantastic new games. I will experiment with Space and possibly Sea travel/combat using it and update you with any major issues if they arise. If it doesn't work that's fine... I would want the plugin anyway. It might be months before I can fully playtest it btw. Thanks again.