Yeah, Toadstool Tour was peak. Good amount of content on its own, then even more added in once you link to Advance Tour. It's a shame that they will likely never emulate the transfer pak on NSO, or GBA-GC link cable if GC ever makes it in.
Id argue Mario Golf Toadstool Tour is peak but otherwise definitely a shame. Very excited for TTYD on switch though, been holding off on buying the gamecube version.
Shame they're holding out on the GBA Mario sports games. They really are the peak of the series. Nice to have dates on Paper Mario and the Luigi port though.