Mario Tennis: Power Tour
Game Boy Advance Cameos
Psynergy Defensive Move
One of the custom defensive power shots causes a giant hand to come out and catch the ball while the screen flashes different colours.
This refers to the Psynergy moves from the Golden Sun series. Both Golden Sun and Mario Tennis: Power Tour were developed by Camelot.
Submitted by PyroGuy128
Great Fairy
One of the NPCs in the game says:
They say if you do a lot of practice swings, a Great Fairy appears to reward you. I fell for it at first, but "it's a secret to everybody", if you know what I mean
Great Fairies appear in The Legend of Zelda series to reward Link. The "It's a secret to everybody" line was also first said by certain characters in the original The Legend of Zelda.
Submitted by PyroGuy128
8-Bit Mario Picture
In the office of the President of the tennis club you can see a picture hanging on the wall of 8-Bit Mario as he appeared in Super Mario Bros.
Submitted by PyroGuy128