On that note, why not just make such mods able to alter the teambuilder when they are the selected metagame if said metagame is supported on the current server, similarly to the way they modify the battle itself?
...I know I've been a pill about this suggestion on the IRC... and for my stubborn behavior, I wholeheartedly apologize to anyone whom I've frustrated; but, I figure that if I talk about it in a different setting and in a different mindset, I might get different results. I'll let you know: I'm a (novice) programmer myself, so I can only guess how tall an order my request must sound like to you. Just know that I can be patient regarding a feature like this, despite anything I've said before. More than anything, I'd just like to know whether such a concept is or is not possible with the way Showdown is currently coded. If it is, I wouldn't mind learning it at all... and though I am a relative novice as I previously, anyone who remembers either Captain's Modded Server or Snowy Mountains on Shoddy Battle is likely well aware of what I can do when I learn.