I'll skip the most obvious moment of the final episode since I'm sure many others can describe it better.
On a lesser note, while the first half of XYZ handled TR badly, the second half was much better handled. They only did a handful of their usual Pikachu-schemes (most of which were at least more creative and blended into the plot better than the two dozen or so shoehorned ones in the first half), otherwise they were absent altogether to give Ash full focus or in off clock roles that used them rather well (the Flare arc and the public Tripokalon being obvious cases). Perhaps most amusingly, during their last curb stomp a few episodes before the finale, they even lampshaded they didn't really have a chance against Ash's currently overpowered squad, and actually learned to fold 'em, spending the final few episodes doing their own thing and having a new plot to keep in Giovanni's graces until Ash inevitably resets his team in Alola.
As a result of this, Inkay and Gourgeist also got the cathartic bone throwing of waltzing out of Kalos happily rather than being last seen blasted off like the previous squads.
On a lesser note, while the first half of XYZ handled TR badly, the second half was much better handled. They only did a handful of their usual Pikachu-schemes (most of which were at least more creative and blended into the plot better than the two dozen or so shoehorned ones in the first half), otherwise they were absent altogether to give Ash full focus or in off clock roles that used them rather well (the Flare arc and the public Tripokalon being obvious cases). Perhaps most amusingly, during their last curb stomp a few episodes before the finale, they even lampshaded they didn't really have a chance against Ash's currently overpowered squad, and actually learned to fold 'em, spending the final few episodes doing their own thing and having a new plot to keep in Giovanni's graces until Ash inevitably resets his team in Alola.
As a result of this, Inkay and Gourgeist also got the cathartic bone throwing of waltzing out of Kalos happily rather than being last seen blasted off like the previous squads.