Hiya!
We're recently reached high enough level for our party Wizard to cast True Polymorph and being the sort of player he is, he's itching to give it a go. "Itching" as in bugging my Monk in-game to let him polymorph me and out of curiosity, a little boredom and the certainly ensuing hilarity I think I'm going to let him do it. However, we're curious as to what constitutes "game statistics". Is it just your base stats? Stats and racial features? Is is your entire sheet? Somewhere in between? I haven't seen a clear consensus on it and while that certainly might be a place where the DM gets to make a ruling, but until next week I'm curious if you folks have seen any uniformity or any official rulings? Is a level 15 Wizard still a level 15 Wizard in addition to being a Green Dragon?
Easy. Game Statistics = "something a game mechanic can be applied to or otherwise used". Meaning...Ability Scores, Feats, Skills, Hit Points, Saves, etc. Non-Game Statistics = "all the fluff". Meaning...well, all the fluff.
Getting turned into a Green Dragon means you flip open the MM and look at the appropriate CR Green Dragon for
everything...except your alignment and personality (re: the "fluff"). Can you use Open Hand Damage as per your Monk Abilities? Nope...those are definitely "game mechanic" stuff (re: the "game statistics"). Do you have Ki abilities? Nope...those are also definitely "game mechanic" stuff. Can you speak and tell the evil bandits to "leave this wood and never return, for it is under my domain now!"...yes. That's all your personality and alignment...nothing to do with statistics or game mechanics.
Yes, it really is that simple, IMHO.
PS: From a purely gaming perspective... polymorph is geared to be used to hide-in-plain-view, overcome environment, spy or sneak into areas, and all that kinda thing. It is NOT geared to be a means to "get tougher than you normally are". So, my rule of thumb is if saying "Yea, you can use that ability/spell/whatever as an Umber Hulk" suddenly makes you better at your core class ability/spell/whatever because you are now an Umber Hulk...then the answer should be "No, you can't use that ability/spell/whatever". This way the DM can always make for niche exceptions to the 'rule'. But blanket "Yup, you can" is going to cause you nothing but never-ending migraines and bitchy-ass power gamer tirades anytime you do say "No".
^_^
Paul L. Ming