was there someone who wanted to make a gba version of fetd (the tower defense thing) idk here's what i did anyway
At its core, it's just a bunch of enemy reinforcements with thief AI and the pick skill running after an invisible chest, since this AI will try to move towards things to open and only attack if blocked.
When the game changes turns, it gives player units a non-team-attacking berserk status that reduces their move to 0 . There's an item that cures this status and gives them a 1-turn status that comes with Canto, to allow them to move again. Probably also achievable by giving the convoy a warp staff or something.
As for some more details of implementation...
Said chest triggers an event that reduces the convoy's HP by 1, and is re-usable. The convoy causes gameover on death, of course.
When an AI checks what weapons it has usable, it only checks the first slot, so they don't go wasting siege tomes or using javelins when other options deal more damage.
The convoy has a skill such that, when the game goes through units to grey them out, it gets set aside (via status) so it can be instantly refreshed. It may be easier to just make it never grey out though and other PCs only grey out if they attacked idk also all PCs have 100 move
Also, during enemy phase, the convoy turns into team 4, which is set to be aligned with team 2, but has team 1 colors, so that enemies can walk through it.
NPC phase is skipped just by making the turn change code set the team turn to 1 if it's 3. This is so buyable units don't attack stuff, and it also helps ensure the convoy doesn't get an awkward team 4 phase all to itself (but it's probably better to just make it change back at the end of enemy phase)
On a related note, all enemy units have a skill that allows them to walk on their spawn/target terrain tiles, which normally act as walls but with crazy avo/def boosts.
*various skills and stuff that are specific to my version, also note that enemy units have huge innate offensive boosts to discourage walling*
Trading is set so you can only trade in one direction, but it's a little bit broken. I don't even remember what I was trying to do lol oh I think maybe I wanted it so units had to trade items to the convoy instead of just giving it stuff to sell, since there are two copies of the convoy unit, so that they can share inventory, so you can buy stuff with one and transfer it to the other to give to units.
As for eventing, there's one variable that stores how many turns you've spent on this wave and one that stores how many turns this wave is, which the objective window reads, along with gold (you gain gold every turn, and whenever any unit dies--extra gold for bosses) When they're equal, the objective window tells you there's a wave incoming, and the game calls the next reinforcement event yadda yadda
Player units have an extra command to suicide. I don't think Knights can do it though.
aaaaand i think that's about it? idk how much of this stuff is directly portable to gba but yeah that's how i did stuff so