But if the sequal had the same battle change as in D/P, then I'd rather it never be made, no matter how good MD is.
why should that bother you? About the only confirmed major change to the battles in DP is assigning individual attacks to physical or special status, and that shouldn't matter anyway considering 1) It's very easy to raise stats in Mysterious Dungeon (hell, there's a limit of 999 on every stat. You're unrestricted on the amount of vitamins you can give, neither), and it's not like you have to be at an insane level to get through the game. 2) Mysterious Dungeon doesn't have competitive play.
Given, when you take into account those dungeons that temporarily reduce you to level 1 (a feature that I think exists in several Mysterious Dungeon games), the first two points I made can be null and void. However, that doesn't matter either when we get to #3) Pokemon have different level-up stats in Mysterious Dungeon than the main RPGs anyway. A Pokemon such as Tsubotsubo could actually attack worth a damn in a game like this, and evolution is, for the most part, little more than for aesthetic purposes. Why not check out
these guides on Gamefaqs (particularly "Level Up Stats" and "Rescue Team Pokedex") for a good idea of what kinda (natural) stats each Pokemon has in this game. It's very much different from the main RPGs, for example, the Casey line actually has a considerable amount of physical attack power, the Wanrikii line has a lot of special attack power. Meganium will seem greatly overpowered compared to the other starters (except maybe Jukain), some unevolved Pokemon will be stronger than their evolved forms, several legendaries will seem greatly underpowered, Dokucale will be more offensive than Agehunt at level 100, etc. Basically, it takes everything you know about Pokemon stats, throws them out the window, and rewrites them completely.