This sounds like a MUGEN full game idea......
There are some ways to make a MUGEN character being able to jump on/off a "platform" in MUGEN.
One is respective to P1 (player) ==>> more control.
Another one is respective to P2 (enemy) ==>> less/limited control.
For P1 (player) self hard-coded part my Custom FC Upa has this feature: jumping on/off a floating Mini-Zai. But it only works for P1 (player)........
For P2 (enemy) general coded part my Custom GNG Lucifer has this feature: jumping on/off a Lucifer's knee(s). But it only works when P2 (enemy) does not have some special MUGEN code that makes him/her/it invincible, and/or always prevents him/her/it from "floating" or "skywalking".........
Simply put, such platform on/off feature is best for MUGEN full games only (very not perfect indeed)......because current MUGEN engine does not officially support this feature........