From the days when game company's actually added programming and cool new modes to their arcade games, rather than just slapping the ROMs in an emulator and calling it good, Capcom gives us Street Fighter Alpha Anthology, containing the main Street Fighter Alpha games, Alpha, Alpha 2, and Alpha 3, plus Alpha 2 Gold, which added Cammy, the secret unlockable Alpha 3 Upper, which added another handful of characters, a new game, the secret unlockable Hyper Street Fighter Alpha, which is really just a VS mode of all the other games mixed together, with new and rather empty backgrounds, and, just for the heck of it, Super Gem Fighter Mini Mix.
Since these are arcade games, there is no World Tour mode (from the PlayStation version--see entry 1034--and later the Dreamcast version--see entry 1033), and no Alpha 3 Max, from the PSP--see entry 1032.
There are training modes, easy access to the arcade 2-on-1 "Dramatic Battle" modes, Survival modes, a hidden "Survival Dramatic Battle" mode, VERSUS 2P (and CPU) modes, secret option menus where you can tweak arcade-style dip-switch settings to simulate various ROM or ROM-style revisions and options--such as turning blood on, or turning off counter-hit full-screen flash FX, a crucial setting for me, as otherwise the fights in Alpha are filled with nasty flashing effects that render them unplayable for me as they can give me migraines. 8P
In fact, with similar full-screen flash FX laced throughout the fighting system (they're also on guard breaks, for instance), the games' UI--character and stage selects, and transitions between rounds and stages--and even some stages--the storm-swept plains in Alpha 3--and characters--2P Balrog's intro, for instance, or one of Cody's win animations--the games would still be unplayable for me were it not for yet another hidden mode: a secret VERSUS (or VS CPU, if you've set 2P to CPU in options) mode of non-stop battles between random characters, cycling through a fixed order of game stages.
In that mode's pause screen menus you can choose which characters the 1P and 2P sides can randomly choose from, and, in the Alpha 3 and Hyper games, which modes and "-isms" they can random pick from--this is key for me, because Alpha 3 has a "Classic" mode that turns off things that trigger full-screen flashes, such as super moves and guard breaks.
So, I can play Alpha 3 Upper in the secret VS mode against the CPU, both of us set to Classic mode only, in 1 round matches (otherwise the flashes between rounds are hard to avoid), with certain characters turned off, as long as I remember to look away (and pause my recording for YouTube) between matches--oh and during the 10th and 17th matches in the stage cycle, which are the lightning-laced storm plain stages. ^_^
Played in that way, it's a rather bare-bones fighting system. The AI is suspect, with lots of gaps in its hazard avoidance (you can just uppercut a lot of the characters repeatedly as they stand up, even on the highest difficulty). But it has great sounds, and loads and loads of lively and colorful characters and backgrounds:
The game can run in progressive 480p mode. You can turn on or off a smoothing graphic filter, but there is always an odd, secondary blurring effect on everything that is stronger toward the center of the screen than at the sides--perhaps this is a side effect of how they scaled the original CPS2 arcade resolution, with its narrow pixels, into standard TV resolution.
Also on the down side, the US version omits pause-screen character move lists--rumor has it this was done to boost sales of the official strategy guide. ; P
The hefty, glossy, full-color official game guide from BradyGames (retailed for $19.99 originally; out of print now, of course, and the cheapest I could get was a used copy from an Amazon seller for $31--and although it is wretched that they removed in-game move lists from the US version to boost its sales, the thing *is* very well produced, very thorough--except that while each character in Alpha 3 for instance gets four pages dedicated to their moves, strategy, and art, they dedicate no pages at all to the extra characters in SFA3 Upper!) calls the secret VERSUS mode "Random Battle Mode."
I guess that's technically the official name for it, then--or as close as we're going to get. Servebot001's excellent secrets FAQ comes close, calling it "Battle Mode" -- https://gamefaqs.gamespot.com/ps2/931620-street-fighter-alpha-anthology/faqs/43035 -- but the only actual references I can find to it as "Secret Battle Mode" via Google currently are in a Shoryuken forum post--which also mentions "the Alpha Anthology book," probably a reference to the BradyGames guide--here https://forums.shoryuken.com/t/random-battle-mode-and-dramatic-battle-mode-codes/17815 , and as a title of a cheat code listing on how to access it, here: https://www.neoseeker.com/street-fighter-alpha-anthology/cheats/ps2/ (by the way, the way to get to it is to highlight VERSUS in the game's menu, press and hold X, and IMMEDIATELY after that--I do it in pretty much a single motion--also press and hold Triangle and R2; if you've done it right, a matchup screen will appear, loading directly into a random match--and finishing a match goes directly into another random match; you control which characters and modes are chosen randomly per match from menus accessible from the pause menu).
Elsewhere I've seen a couple references to it on Youtube--in a comment I got on one of my videos, here , and in the description of this video -- as "EX Versus mode," but I'm not sure where that came from; it's a more elegant--if less descriptive--name, but Capcom as far as I can tell used "EX" as a label for enhanced moves and alternate versions of characters, not modes.