Its tough…
Top 3 average means that for rosters with a couple of All Stars (be they 5* star in a 2* star world or just a couple of PVP MVP 4* Championed), the only viable team will quickly become those 3 characters…
At least if you run off un-boosted levels then the boosted characters might be useful.
The more characters you use to generate the average the more of the roster you make usable, but you reward the existence of having 1 or 2 MVP characters who are massively levelled over the average of the roster.
I don’t know what the solution is… which is why scaling is an odd choice over a fixed level but tiered Gauntlet style approach. Getting it right for everyone is nigh on impossible.
Having said that, my preference for Scaling if it has to be done (ironically not the best for my actual roster given the relatively equal levels I have used) is to go with as high a number of characters as reasonably possible for the average… as at least then if I choose to aggressively level my favourite character, whoever it might be, he/she will always be an powerhouse… which is likely to make me feel good as a player/fan. As I am using the characters I have invested in, but can still use a relatively high number of characters from my roster during the event.
So I would take the average of the boosted characters… at their boosted level at the start of the event.
People with bigger rosters might have unboosted favourites that will be powerful.
People with bigger rosters (inc 2 & 3*) will have lower scaling than people with narrow high end rosters (4* +) and that enables more of the roster to be viable.
It will emphasise better rosters as the big 4* will be a powerhouse, which is fine, but also avoids the impact of 5* on scaling.
I wouldn’t include the Essentials, if you have them then they are always going to be useful given that their boost is greater than the weekly boosts.
Sure the 2* with a 5* star in the roster will likely use the 5* for everything, but hey, that’s still cool right?
It arguably penalises those without the 2* and 1* boosted characters, as they wont be pulling the average down, but then chances are you have a mostly high end roster if you have got rid of the 2* and it might even get people to roster the 2* anyway.
example:
Full Roster, max level but not champed, comes out at an average level of 235 vs the Booster 4* level of 360
Just having the 3 & 4* characters the average level is roughly 300. But these guys also probably have some developed 5* to power through, and non-boosted 4* Champs will be relevant/powerful
A 3* transitioner with underlevelled 4* and all 2* will be looking at roughly average of 220ish, meaning that all their boosted characters and any focused characters will always be useful.
As an idea it has some big issues… I have no doubt.
and Id really rather just have a tiered gauntlet style event with fixed difficulties, so you only get to do what your roster lets you…