Hoping to make your life's design a bit more dynamic!

Like the NES, it depends on the mapper and if the game was already using the maximum ROM size supported by the mapper.
Although it seems that fortunately the mappers are similar enough it may be more easily possible to make a mapper hack if needed.
Unlike with NES, where if the game doesn't have room and is already at maximum ROM size for the mapper, you'll have to make do with what you have.

Does the GB use mappers? I've never seen any mention of mappers in any docs though but I may have missed it. GB expansion is really easy though as you just tell it how many banks you have up to 4MBit (32 banks) and just tack them on and load them as needed. For this game it's set for 16 banks so we can add another 16 easily enough. I haven't seen a GB game that uses 4Mbit yet, it seems 2MBit is usually the most common I've seen.

They call them MBC (or Memory Bank Controllers), but they definitely do use mappers (otherwise, GB games would be limited to 32KB).
At least according to the No$GMB author (not sure how accurate that is):
MBC1 = 2MB (one 5-bit register for the lowest 5 bits of the bank ( = 32 x 16KB, or 512KB), and another that can either select the high 2 bits of ROM bank, or bankswap cart RAM). Contains a bug where ROM banks that are multiples of $20 can't be used.
MBC2 = 256KB (and uses 512 nibbles of RAM built-in to the mapper chip)
MBC3 = 2MB (7-bit ROM bank value)
MBC4 = ????
MBC5 = 8MB (reportedly there is one 8-bit bankswap register, plus another allowing a 9th bankswap bit for a total of 512 banks. However no 8MB games were ever released.)

Ack! Good point, didn't think of those when thinking of mappers (I blame it being too early when I posted ) Never saw anything about MBC3/4/5, interesting. Then again the doc I usually reference is Marat's at : http://fms.komkon.org/GameBoy/Tech/Software.html as that one's good for quick lookups for info. From what I've noticed most of them seem to use MBC1 I believe... although I think I've seen an MBC2 one (Last Bible 2 maybe?) For this game, SD Gundam, it uses the MBC1.

I believe Aretha I and II are MBC2 (and so they can only save one game because they're limited to the 512-nibble in-chip RAM for backup) while Aretha III is MBC1, I think.
I know Aretha I screws up badly in most emulators (loading saved games doesn't work, in some even saving the game causes game-breaking corruption). Though on that one I already dumped the script and sent it to filler. Not the easiest to figure out either.
I wonder if Aretha I is as glitchy on real hardware (such as moving around on the world map a bit to the east of the first town can you to randomly glitch across the river, skipping the first dungeon.
Though a little while ago I got a cart in a "junk" lot, haven't got around to testing.
The other MBC2 game I tried to hack is a dungeon-crawler known as Ayakashi no Shiro. A very small game (only 64KB, half the code/data and the other half are graphics). Sent a few translators the script dump but none have responded back.
Still a bit annoying as I got bugs until I read MBC2 has a bug where you need to bankswap using an address with an odd high byte (like writing to $2100 will work, but writing to $2000 will fail in more accurate emulators)

FYI I haven't started working on it much yet. Just puttered around with the first block. The writing style is terse and my translation memory is not well seeded for the style yet. I haven't forgotten about it though.

Found out it was Sailor Moon R that's MBC2 which means LB2 may be MBC1... but I could still be wrong

I've never had a problem swapping banks as I usually mimic or hijack the code that the game uses to swap banks so didn't know about that bug. I wonder if they all write to $2100 then as that's exactly what SMR does.

And yeah far as translation, I'd imagine a lot of them are as terse (wasn't SMR just as bad filler? And the all hirigana scripts that are the norm too) which makes a lot of people not want to do them I guess.

Yeah, and SMR was all kana too which can be a pain. At least Aretha has kanji. RPG scripts can be drier than something like SMR though. I'm a bit of a Sailor Moon fan anyway so it wasn't too hard to warm up to that one. I'm sure I'll warm up to the Aretha script too. I did for Aretha II on the SFC after all.

And the A-II story is developing quite well. A twist in the beginning 15% of the game really catches a player by surprise. And a super villain is viewed differently as the early party members penetrate deeper and deeper into "enemy" territory.

Some of the characters are quite zany and unique in temperament, and even a few townies are embroiled in various enterprises that spin-off sidequests - some necessary to advancing the game. Technical difficulties with space and compression issues are holding us up a bit at the moment, but these are being ironed out, and I expect Taskforce and I will get rolling again soon. I will send you a stable working A-II ROM as soon as I have one, and maybe this will give you some insight to a tone we can set for both games.

Yeah, sorry about the delay, I kinda got sick again. I'll get my end wrapped up this week.