Gintama

=Cameoed= It's unknown if other series have referenced this.

=Cameos=

Ashita no Joe
Episode 229; When it's finally Gintokis turn in the dating sim tournament, he's conditions are vastly changed to a boxing match! (this scene does also contain dramatic lighting)

Isao Kondo dresses up like Danpei Tange and tries to encourage Gintoki (which he keeps refering as Joe). Gintoki is however every pessimistic about the situation and even says that he has no tomorrow. (sort of reflects how in Ashita Nno Joe, they are fighting for tomorrow)

(Not to mention "Ashita" is tomorrow in japanese duh)

Black Butler
One of the openings had Gintoki, kagura and shinpachi dress up from black butler?

Death Note
?

Dragon Ball
?

Gundam
?

One Piece
?

Pretty Cure
?

To Love-Ru
Episode 101:

Prince of Tennis
Episode 62: