Doamaiger D

Both anime series have short episodes and serve as parodies of other mecha anime. While Gundam-san is a parody of the first Gundam series, Doamaiger D uses a lot of tropes and cliches from different classic super robot shows. Overall, both have a similar charm and humor. 

Both are recent comedy shows, which use many tropes and cliches from anime of similar genres for parodic entertainment. Their stories are quite simple and revolve around the same jokes, but their charm comes exactly from their simplicity. While Doamaiger D serves as a parody of the super robot genre, One Punch Man is a parody of superhero shows and comics, making them quite similar in atmosphere and vibe. 

Both are short anime that parody classic super robot shows. While Doamaiger D uses common tropes and cliches from said shows, Toei Robot Girls has a bunch of girls dress up as classic mecha robots. Overall, both have the same kind of silly comedy and atmosphere. 

While their length is different, both are super robot anime that take most of their ideas from classic super robot anime and present them in a funny and silly way. Both are self-conscious anime that are not meant to be taken seriously and give off a very similar vibe. 

Both of these anime have an interesting stylistic choice going on, as even through they are newer show, they mimic the easthetic of oldschool anime (60s/70s). 

Short anime that features a mecha with food aesthetics. 

Both are short parodies show in retro aspect ratio despite being new anime.