Not as good as the other GBA Tennis no oji-sama games, but still quite enjoyable.
This game (as the other ones for GBA) is a basic tennis game with some adittions and customizations to make the it look more like the serie.
To beggin with, there are 3 options in the main menu. The first one is "Options", which obviously let you changes the settings of the game.
Within "Options" you can change the Game Leve (Easy-Normal-Hard), the second option is to change the background (which doesn't affect in the game progress), there are 7 backgrounds available. And the last one is "Gauge Speed" that lets you change the speed to fill the bar to Normal or Doble.
Another option is "Gallery". This option lets you see pictures of the characters you've beated the game with.
The last option is "Game Start". This, obviously, let's you beggin the game to play it.
Inside "Game Start" there are 2 options. The upper one is for playing solo and the one below is to play with a friend with 2 cartridges(You can play Singles or Doubles in cooperative or versus).
Inside "Solo-Play" you have 3 options.
The First one is "Ranking Match", that rerepresents some kind of "Story Mode". This is the mode that you have to beat in order to unlock the gallery pictures.
The second & third ones are "Practice Match (Single)" and "Practice Match (Doubles)" respectively.
Okay. Time to talk about the game itself.
Before starting, it's better to change the game options to your like, to make the game a little funnier.
In "Ranking Match" you have to choose the character you will be playing this time. There are 8 characters to choose firstly but you can unlock some more characters, as Nanjiroh (Ryoma's father) or Inui Sadaharu.
Once you picked a character you will meet S.Ryuzaki who'll speak for a moment before you start the match. Then your character will show up and say something and then your opponent will speak. Right after that the match will beggin. Before starting, you should choose "Rough" or "Smooth". That will decide who will have the service. The buttons are "A" for shoots and "B" for lobs. Also, you have special shoots that varies depending on the character you choosed. This special shoots also varies in how to perform it depending (again) in the character you choosed (Check GameFAQ to see the list).
Also, another special feature in the game is that you and your opponent can break each other raquets. This is quite fun and gives the game a little more tactic, because you should think about the character you want, a strong one that can break the opponent's three raquets or a speedy one, that can reach any ball and shoot it more precisely. If your three raquets are broken, you will loose and the opposite happens if you break the opponent's three raquets.
That's about all. That's bassicaly the game, so i think i can end this here.
In resume, Tennis no oji-sama Genius Boy Academy is NOT as good as the other Tennis no oji-sama games for GBA (as Passion Red, Cool Blue, Stylish Silver or Glorious Gold). It's highly recomendable to the fans but i don't think it's worth of a very good punctuacion.