You can indeed!
Each section of the Database has a point limit, where you can edit and retag afterwards. On Pokebase, it's 6000 for both. For the Battle Subway, I believe it is 800 to retag and 1000 to edit. Meta has 1000 to retag and 2000 to edit.
The reason not everyone knows about this is purely because the moment you hit 6000 on Pokebase, the easiest to get points on, you are awarded Expert and thus can edit freely. If I recall, only JCM and Slippery Devil can edit on RMT but not elsewhere. Myself and Ayan were also able to edit on Meta before being Experts (Ayan held longest editing regular user for a while and had most points on Meta for any non-expert before I took the latter from him prior to being an Expert myself).