I'm a bit sleepy right now so forgive me if I haven't gone into much depth.
The Super Mario Bros. 3 section should definitely be rewritten. It's written as if it was a narrative with sentences such as "In battle, Ludwig goes into his shell and tries to roll into Mario. Though fast and capable of making stunning earthquakes and magic blasts, Ludwig is defeated and his control over Pipe Land comes to an end." that is definitely a no. The rest of the article may have similar writing problems such as that. New Super Mario Bros. Wii's section is written ideally for Super Mario Bros. 3.
DiC cartoons section can use an expansion and rewrite (for better writing quality) for Ludwig's roles in each episode he appears in.
I think the formatting for the Mario & Luigi section can definitely use some improvement. Don't like the giant gaping blank spaces there.
Mario Kart 8 section could detail his different stats in comparison to other characters in his weight class, as well as talk about his CPU kart preferences.
Puzzle & Dragons: Super Mario Bros. Edition could use an expansion.
Mario & Sonic at the Rio 2016 Olympic Games can use more details surrounding his stats, explaining what a high skill stat means.
Paper Mario: Color Splash section could use a rewrite here and there, I find it difficult to follow it.
Other Appearances I feel doesn't separate headers for each minor appearance Ludwig has made in the game.
Gallery is an empty section, can't have that.
Aaaaaand that might be it.