What are the mangas with more volumes that have been translated into mangadex.

MD doesn't translate things (well at least the majority of the titles here) they just host said translation most of the time.

As for titles, it's most probably Ippo.

uploaded would have been a better way of saying it but honestly who cares.

I'd say JoJo's Bizarre Adventure is up there too.

Chapter, page count, or as a series?

/Jojo' Bizarre Adventure/ 1-6 are around 20 pages per chapter, 7-8 are 40 pages per chapter.
Disclaimer: Some Chapters may vary and exclude some title cards on top and bottom could equal to 18-19 instead.
Part 1: 44 Part 2: 69 Part 3: 152 Part 4: 174 Part 5: 155 Part 6: 158 / Part 7: 95 Part 8: 91-