Talk:Upgrade/@comment-4486271-20160602162258/@comment-11249456-20160708203152

To clarify, many players end up short on Rare Medals, so from a medal optimization perspective, it's better to amalgamate your Metal Slime to create Medal Girl for 1500 medals than it is to use the Metal Slime for leveling.

As for the "other options" being hinted at, instead of using metal slimes, you would either level your URs via fighting F/AWs or via fighting in Elemental Hall (leveling via fighting is good if you're also aiming for max Friendship Level anyway), or you'd use HRs, Rs, and Slime to level them. The extra patient might use HNs as well.

In the case of using HRs for leveling, you will wind up with a lot of spare 1* Rs just from F/AW hunting. For me personally, I use HR Android (which is useless for medals anyway) and I keep the ones that you can Evolution Accident (you probably have lots of extra Turn Over Arcana from fighting F/AWs) and use the failed accidents to level URs.

Personally, I'll use metal slimes if I have them (I only max out skills, so I have lots of extra rare medals), but I have to rely more on HRs and slimes because, as kushieda minori also points out, metal slimes are fairly rare.