As someone who played the original version of it, yes the difficulty will increase.... There are some dreaded dungeons..... urgh.... some dreaded dungeons.... I still wonder how the hell I beat that Jirachi one..... hated every second of it.... gonna have to do it again... oh god..
What about celebii...?
At least, it's becoming your friend by the time you meet it, unlike jiraji, which you have to fight it, after striving to survive 99 floors and retain friend bow, albeit celebii level is much harder...