There are a few bugs associated with Monster Rancher Advance 2, most of which have to do with writing to the memory of the game. This is a list of known bugs, with workarounds if they are known. It goes from funny to serious problems for your game. If you want to report a new bug, post it in the correct Q&A and I will add it to the list when it has been tracked down and verified.

Note: The occurences of these bugs are few and far between! Do not panic, and do not think of this as a reason to not buy the game. MRA2 works perfectly fine for most people.

Hospital Bug
Normally when you go to the hospital, Talt will say "Hello, (enter name here), what can we do for you today" or "Hello, (enter name here), Dr. Kohak is here today.

However, if you go there without a monster instead of using your name, Holly will tell you "Oh (name of the last monster you were with), It's meaningless to come to the hospital without your monster. Please come back with your monster."

Work Around: don't go to the hospital without a monster :p.
Effects it has on your game: none, it's harmless, and depending on the name of you monster can be a good way to get some laughs out of the game.

Tournament Bug
At times when the screen goes black after your monster wins a tournament, it will stay that way and the game is locked. If this happens, then switching off and turning back on will bring back your game at the last save. However, it seems there is no way for that monster to fight and win that tournament successfully.
Wourkaround: the next monster you raise should have no trouble in that tournament.
Known Suspects: The Winner's Cup of the Big4 is the most common place for this to happen, especially if it is the last of the big 4 you need. I recomment not saving this one for last.

Coach Bug
This one is harmless, and actually quite good. Some people are working to find a way to reproduce it at will. Basically, a coach will want to retire after 26 years or so of service. Sometimes, Holly will tell you he's gone, but when you go to train some or all of the drills assigned to that coach will still be active and that coach will still be there. You cannot change the coaching points for that coach, and if you replace him, he's gone forever, but he will stay.
Personally, I have had it happen once, and the coach is still in service on one drill even after over 100 years!!!
Workaround: replace the coach if he stays but you don't want him, if you think you have a way to get it to happen all the time, get in touch with us.

Studio Bug
Sometimes, maybe when testing several combinations, the studio can go haywire. If this happens, no combinations are possible.
Workaround: Restarting your GBA seems to clear it up.

Flare Orb Bug
There are certain items that are crucial to the game, or at least to unlocking all breeds(Phoenix in this case). Most notably the Flare Orb you get early in the game from Canute. However it is quite possible to accidentally feed this item to your monster. If your monster is willful and you feed it things it does not really like, Holly will say it wants to eat X instead, is that OK? X can be anything in you inventory, and the default answer to this question is YES.
Workaround: Don't rush through the feeding cycle at the beginning of the month!

Overload Bug
The most advantageous yet dangerous bug in MRA2. The way the timing is set up on the Save/Load process and the way item bonuses are applied leads to this bug. There is detailed info on exactly how it works is in Q&A or the Raising Methods Section. What's the Problem you say? Well it involves almost weekly saving and reloading ove the game, several times in succession. Essentially weeks of realtime Saving and Loading is compressed into a few hours of play. This wears out the cartridge memory and can lead to a corrupted save file or a game that may not save at all.
Workaround: Think long and hard before you use Overloading to max out a monster.

Octochrome the Unattainable Rare Monster
There is a glitch in the game which results in the password which is supposed to unlock the Octopee rare called Octochrome making instead a ducken type. This has been fully researched, a bit of incorrect coding in the game software causes the problem and there is no way to fix it. Octochrome is therefore unattainable without the use of a cheat device.

This is a lot of gloom and doom for one post, but like I said these problems are really few and far between.

Thanks to: Infernus