As a general rule sports games are about as ignored by ROM hackers as they are by the general game buying public in charity shops and other sellers of second hand games. Megadrive/genesis likely more than most.
To that end I doubt you will find any documentation on it, much less premade utilities. The token quick scan of documents, the wiki and the utilities section of this site has not a lot. I assume you would have found anything external if you went searching.
It can make for a nice introduction to hacking however.
Generally speaking a team roster is not all that different to a roster in a RPG -- bunch of characters with a bunch of stats, allowable moves/weapons/spells, names, position/class and general appearance (or maybe number if this is a sports game)... Indeed with so many characters and likely few of them having any unique abilities then you might even be better off and find it is all just numbers rather than something fancy baked into the code.
Finding such things in games can be slightly trickier than some other things but still within reason
Generally speaking there are two ways to do a stats table for characters
1) You have each character and each stat they have one after the other.
2) You have a table for each stat and then each character gets a value in that table.
There are perks and benefits to both approaches, and slight twists you can do (though most of those won't show up until somewhat later systems) but those are the main methods you will see to represent such things.
I would usually start by trying to find the stats in RAM (load different teams, or swap around characters with different stats and search for those) using a cheat search. If you are lucky then any character names will also be in the same tables (sometimes they are separate) so you might be able to do more text search methods (possibly even on the ROM)
Anyway when you find that then most times devs will store things the same in the ROM as they keep in RAM (doing maths when the code is running is far less fun than having it done beforehand).
If there are cheats for max speed or something then they will often attack such things so you might be able to skip that if there are some codes already made. If there is a training/RPG elements aspect then even better.
If not then you get to trace things back to the ROM -- find the location of stats in RAM, set a break on write to that location, hopefully when it pings up saying something wrote here and here is what is then in the preceding instructions will be where it found it in the ROM. https://www.romhacking.net/documents/361/
is my usual suggestion for tracing. It is for the GBA and for a command line emulator, nor do I know what we are suggesting for a megadrive/genesis debugger these days.
If you really must then you can skip finding stats in RAM the more conventional way and do something like note pixel or virtual map location of a character and set a breakpoint for anything changing that, somewhere in there will be a variable that accounts for individual speed of a character. If they have HP of some form then that also might be useful.
Anyway from there you should know the location and general layout of the stats tables. Can edit things if you want. Names should be much the same, and possibly even taken by a basic relative text search ( https://www.romhacking.net/utilities/513/