I'm wondering about maximizing meter gain for characters without a battery ender. During a combo, does the attacker gain meter more or less proportionally to damage dealt? Or is the game biased towards some moves gaining more shadow meter per damage dealt than others?
That said, most combos don't build a ton of shadow meter; to verify this, just look at the meter you build when you are comboing someone after round 1, you usually only get about 20% of one bar for the entire combo of heavy autos and linkers. So whatever advantage might exist on a per-move basis is going to be pretty minimal.
In general, the best way to build meter for characters without battery enders is to make them block moves in neutral. You get more meter if your move was blocked than if it hits, and this is especially true of projectiles. So someone like Mira, who has no battery ender, builds a ton of meter because she is constantly making you block st.MP xx light bats, and this string (and others) just generates a ton of meter for her.