Well, since I'm curious, I'd thought I'd figure out Serenes' preferred method of handling shapeshifting units such as Manaketes or Laguz in FE games
Method A: Dragon/Beast Stone
Pros: constant Stat buffs, generally among the more powerful weapons in the game without forgeing
Cons: stones are very rare, with several games only giving you one to work with. Limited durability in most games.
Method B: Transformation gauge
Pros: Transformation gives movement bonuses in addition to other stats, I'm not sure but I believe the stats boosts while transformed are higher than those of stones. It's been a while since I've played Tellius, so my memory is foggy there
Cons: Stat buffs only apply when transformed, one either has to wait several turns to transform again, let themselves in their weakened state be attacked several times, or use a item to boost the meter in order to transform back into animal form and thus get their stat buffs back
My personal preference is Stones, due how much more reliable they are IMO, but I'm curious as to everyone else's preferred transformation method from a game mechanics perspective.