Since I started playing ST a few months ago I wanted to have a training mode on MAME like the one available on the Sega Dreamcast port. I collected all the available training mode cheats but none of them convinced me, so I studied all them, fixed some of the glitches and finally end up taking the best of each one to write my own.
The first usable training mode cheat was made by Pasky, he explained it very well in this comment, the main problem with his cheat is that the stun meter stops working properly after the health bar is recharged and the cheat has to disable stun, so the players never get dizzy. The cheat is interesting because he hooks the game code to make it jump into his own subroutine that refills the health bar for both players. This cheat only recharges the bars after hit damage, but not after throw damage.
After that, there was a new training mode cheat made by d9x/dammit. It is way easier because it only recharges the health bar when the dummies are at a certain state (for example after being hit). We can see the value of this state at memory address FF8451 (or 0x400 more for P2). This allows the stun meters to work properly, so characters can get dizzy normally, however it still has some glitches like sometimes when the health is recharged opponent gets hit or pushed back.
In both Pasky and d9x cheats, the health bar can’t be empty (if this happens the round will end). This is one of the things that bothered me, because you can’t get an idea of how much damage you would do, for example with a 5-hit combo, as the bar is refilled very quickly after every hit or when it reaches a certain value.
Not long ago, jedpossum published a new training mode, which has the particularity that even after the health bar is empty, the game continues. However it has a few new glitches, like the player’s vertical position after a wall throw is sometimes messed up, and there’s the K.O. slowdown present when the health bar reaches zero.