This particular Medabots game spawned from the anime series, but let's ignore that for a bit - let's actually take a look at the game, ignoring the license it was built on. Medabots is a turn-based RPG where the highlights are robot battles and customization. You build your own robot from whichever pieces you want (there are sets, but you can mix-and-match), you give it a power source (a Medal, hence, Medabots) and you're all set for battle.
Story
If you have seen the anime, the story of this game is similar but only up until a certain point, and with some added material. You start off as Ikki, medabots fanatic, who goes out to buy food with a big money bill but for reasons out of his control, ends up buying a tinpet (a robot skeleton in which you assemble the medabot parts) and a set of Metabee/Rokusho parts, an outdated model of Medabot. His mother gets angry, but his father actually gives him a brand new medal, and you're able to start your own adventure. From there it just advances with different stories all centered around Ikki and the Rubberobo Gang, kinda like the Team Rocket of these series.
Maybe you should show her your medabot.
The dialogue is pretty good! There are lots of funny moments and lighthearted chats. The game manages to not take itself too seriously and it's great at that - it never gets too "dark" or anything, once again I compare it to old-school Pokémon.
Gameplay
This game is turn based, but kinda weird. Every Medabot in battle start out on opposite rows, where you input commands, and only after running to the center of the field they execute their orders. This makes for some interesting twists and abilities; for example, there are Medabot parts that only hit when the enemy's showing their back, but deal critical damage. It works mostly like the Active Time-Bar on older Final Fantasy games with a few changes.
Wolverine gets ready to kick some serious robot ass
You can control 3 medabots in total. Your options in battle are: Medaparts, Medaforce, and the others are standard RPG options (checks status, flee from battle, etc.). In the Medaparts menu you select one of your four medaparts and they will do their ability - each medapart is divided in Head, Right Arm, Left Arm and Legs, and they each have their own abilities (the legs medaparts are mostly for acting faster since there are terrain changes, and every one of them charges Medaforce if you select them in battle).
Medaforce is kinda like a super-special attack - there's a medaforce bar, from 0 to 80: it fills up by 20 everytime you're attacked, or you can charge it yourself by 40 points if you select your leg medaparts (you won't do anything else that turn obviously). Each Medal has 3 different medaparts, and they all have crazy effects, ranging from a classic super energy beam, from a boost in speed to all friendly medabots. Your Medals will get different Medaforces as they gain levels, and also "evolve". Each medal is based on an animal or an entity, and for example, the Kabuto (Rhinoceros Beetle) Medal starts out as a little worm but eventually grows to a full-fledged beetle. It's worth noting that the robot parts don't level up; only the medal.
Each Medal has stats you must level yourself by using a medapart of that type over and over - most medals also have a "STAB" of sorts - they gain bonuses when coupled with medaparts of the same type. However this boost is minimum so you shouldn't fret over using same type medals all the time!
QUEEN, the Peppercat model.
Also, the main difference between versions are different Medaparts, Medals, bosses and starting medabots. Metabee starters will start with a rapid-shooting type medabot, while Rokusho owners will get a melee specialized medabot complete with sword and mace. Rokusho game might be slightly harder in the beginning since Rokusho is much more fragile than Metabee, but imo gets easier along the way. Any of them is good for a start, although you will want to finish both.
Graphics
You can't expect much from a GBA game, but goddamn if this isn't one of the prettiest GBA games out there. Every Medabot is animated in an amazing way, they all move like 'real' robots making battles a joy to watch.
The overworld is very colurful, but nothing to write home about. The real deal is in the battles. Also there are some cute cutscenes taken from the anime which are very appealing to the eye. In general, this is a very neat looking game.
You sure don't wanna get hit by those!
Just Give me a Score or a Conclusion or Something, You Stupid Shit
Lightning and Robots! Can you get more metal?
Fine, sheesh. This is a game that any Pokémon player will enjoy - especially if they have a thing for robots, like me! There are -lots- of intrincacies on Medal Stats and mechanics in general, not to mention the enormous quantity of Medals, Medaparts and secrets and easter eggs in general. It's a very rewarding game, and it will make you want to search every corner for a new Medal just to complete it 100%. Lots of longevity for a handheld game, will definitely keep you occupied for a long time.
I love games that combine RPG elements with gameplay other than "push button to input order".