Mhh.. I'm not really sure about the powerlevel. no permanents is a hard condition which excludes you from alot of stuff. But on the other hand, it could be really interesting to play with.
What will definitely be powerful is deck manipulation. Something like
Brainstorm should really come in handy in order to place the next spell that will be casted for free. Besides that, in some cases you can put some cards from your hand or top of the library on the bottom of it, but that depends much on the spell you will cast with codie's ability.
Besides that, you will definitely need some cards that generates tokens in order to get hands on some blockers. Beatdown isn't the best strategy for edh because of the massive lifepools, but sitting there without blockers basicly invites the table to do this.
/edit: already got an first idea: A
doomsday stack with any extra turn with cmc <7 and
approach of the second sun. Rough gameplan: get rid of the first 3 remaining cards within the library, cast approach with you commander, cast the extraturn for free. since the approach is the only remaining card in your library you can draw and cast at your extra turn you can play it again and win.
This feels a little janky, at least until now, and we also have 3 open slots for the stack, but I think that's already something worth to work out.