On archive.org, search up "wario mario manga." There are scans of interior pages and covers of Wario's appearances. I would also search the stuff from that thread, such as Super Mario Kun, Mario 4koma, and the Club Nintendo magazine.
I want to replay Wario Land 2, but I feel like I should wait for it release on NSO. It comes from some irrational obligation to boost the play stats for Wario Land games for Nintendo to see.
Out of the Woods even appeared in the original Mario Tennis and apparently the game boy one had it too but it's been too long for me to remember, now I want to play it again, that's the only Mario Tennis I had
With a track record like that and...