A Guide to Ability Learning

Is there a way to set Dance Learning by Level Up ONLY?  I wanted to give this ability to Locke, but I didn't want him to learn them via the Battle Maps.

Yes. You would need to check if the character is Mog in the natural magic/swtech/blitz learning function ($C0A17F) then add some code somewhere where is free space where you would jump to if the character is mog. Basically it would work like natural magic but you have two tables of 8 entries, one for the levels where the dance are learned and one for the dances IDs. You first check mog's level, if it match to one of the levels in the table you load the corresponding dance and turn the corresponding bit of that dance ID in $7E1D4C (in a similar way to $C25EED). You'd also need to NOP $C25EE5-$C25EFA to not learn dances the normal way.

If dances are listed in the order they're learned, as with Blitz and SwdTech, it's doable with only one 8-entry table of levels at which you learn a new dance. Blitz and SwdTech reference only their level-at-which-learned table in C2, for leveling up after combat, and the recruitment/level averaging code in C0 references that same table and a shared bitfield table (C0/A22C) that you could also use for learning Dances.