A max level clause is interesting considering that you could have legal Mew and Mewtwo in addition to fine tuning Chansey/Lax. "Overleveled" Pokemon would also be an in-game way you could boost stats to recreate Tier Shift, or even rebalance the game to make as much of the fully evolved Pokemon viable without actually changing anything in game or cheating beyond having level 101-255 Pokemon.
Trouble is, Smogon has never used a level cap to balance Pokemon, and doing so for RBY would make it inconsistent with later generations. I like the idea of it, but it doesn't gel with how Smogon's done tiering for its entire existence. It could be done as a non-OU metagame though, and letting players play RBY with the Pokemon they want to without getting absolutely destroyed by the OU monsters or being allowed to play with Mew & Mewtwo would probably appeal to plenty of people.
Regarding Wrap, I have only heard #BAN/#NOBAN, but no discussion on my Wrap Clause proposal, which would make it illegal to use partial trapping after a cycle of partial trapping is completed. This would entirely neuter AgiliNite (T-Wave Dragonite is where it's at anyways), and all partial trapping users would be able to use the moves for chipping a Pokemon or pivoting, but NOT for cheese sweeping. Additionally, Wrap Clause can be enforced on cartridge without issue. This seems like it'd be a sensible compromise, preventing Wrap abuse without outright removing a whole part of RBY. Also want to point out that Wrap is also not implemented properly on Showdown yet. On sims, either both players are informed when Wrap has ended, favoring the wrapped player, or the wrapped player is not informed while the wrapping player is, favoring the wrapping player (how Smogon implements it now). How it should be done is a "FIGHT" button should be introduced. To see if Wrap is done, either player would first click "FIGHT" to see if they can move, and then if they can, get to choose another action based on the knowledge they have, otherwise they are locked into using Wrap/being unable to move. The attack options could be left as is during Wrap for a "shortcut" for FIGHT + use move (if allowed because Wrap ended) to speed things up.
Another option that shouldn't be considered except under extreme circumstances is ACE, outside of maybe fixing game breaking bugs such as Counter desync or adding clauses. ACE has evolved to the point that you can save ACE with your save file, permanently "patching" RBY, and even transfer ACE virally over link battle. I believe it is possible that you could do quite a lot with ACE, including introducing Sleep & Freeze Clause, fixing patches, and heck, maybe even add Pokemon to the game that shouldn't exist yet (someone already did this for Ho-oh). With how extensive ACE could modify RBY along with the ease of spreading a patch, any changes that are agreeable to the community as a whole could be possible on the original RBY cartridge.
As for changes to the meta with existing rules, I'm in favor of Wrap Clause > Wrap > Ban Wrap, Tradebacks (after thorough testing) > No Tradebacks, Leave Reflect Chansey/Snorlax > Ban Reflect > Ban Reflect + Recovery > Ban Reflect Chansey/Snorlax. Banning Reflect is comparatively simple, from playing tiers equivalent of UU to ZU on Pokemon Perfect I can't recall Reflect being used much outside of a tank Clefable set in RU, and in the modern OU metagame, it is very commonly seen on Snorlax and Chansey yet a rare sight on any other Pokemon, including on Alakazam nowadays, so banning Reflect wouldn't be horrible. Additionally, Harden and Defense Curl exist too, so many of those Pokemon that occasionally used Reflect would still have access to a nerfed version of it. Banning Reflect + Recovery kind of works since it's about banning a troublesome combo, like say Swift Swim + Drizzle, and not complex bans on specific Pokemon. Banning Reflect Snorlax/Chansey conflicts with Smogon's stance on complex bans, and it introduces the "slippery slope" issue.