So, the concept is having a gundam/mecha body. This can be either temporary (limited time) or permanent (has to live in it). It can also be either original sized or scaled to human sized (preferred). The good thing about scaling them to the size of a human is that there are way more crossovers you can do with them. It also helps with the power scaling (maybe), considering everything will be way smaller.
So the idea is, making the user stronger overtime while giving them powers like trans-am or the satellite system. (I have never watched gundam outside gundam build fighters, I am not an expert. Do not trust my opinions.) The user might gain these either through the normal system rewards or just setting them up themselves without any system (might be really hard).
This just sprang into my mind for whatever reason so yeah, now it's here.