Flying Little Tiki is a ball of stats. On most units, there's at least one boon and one bane which are relatively inconsequential, sometimes more. On Tiki, all boons are good, some better than others, and all banes are hurtful, some more than others.
Boons:
Atk: for OHKO on dragons and just better damage generally. However, not a good idea to depend on OHKO against Nowi; that girl has lots of HP, doesn't always dump it (-spd +def is somewhat popular), probably outmerges her (which grants both res AND HP), and might use close def with red Naga-based weapons in mind.
Spd: she's super fast to begin with; with chill spd and 6-10 points in flier (or dragon) buffs she has natural doubles on the fastest of our glass cannons
Def: quite solid to begin with, especially with the prf; she can get into the upper 40s if she wants with A-skill and seal, not to mention more emblem buffs. Significantly, she sits around the edge of the OHKO range for some of the Falchions, so each side's IVs and builds can decide the matter.
Res: extra padding against dragons or, if using DC, mages. Might enable her to resist ploys, especially with summoner support.
HP: she doesn't have much of it, which makes sustain builds harder to use without summoner support. She's also fast enough to expect to avoid doubles from most non-brave weapons. More HP is good.
Banes:
Atk: harder to OHKO dragons, and generally worse damage; also weakens aether-based sustain builds. However, her atk is quite decent for targeting res (because melee units rarely have more res than def) and having adaptive damage against ranged units, and emblem buffs should be enough to bring her atk to an effective level.
Spd: barely needs explanation - 33 spd is not hard to double; she loses her potential for natural doubles against super-fast units; becomes QR-dependent.
Def: probably the best bane because she can afford to give up a little of it, but her otherwise her def really is quite solid, and with a bane it's only good.
Res: superbane, and makes dangerous for her to take a hit from blue dragons, who she could probably double and KO. Also makes for poor mage tanking. In particular, she might survive a hit from a Naga tome under the right conditions if she keeps her magical bulk.
HP: with 37 spd before skills or buffs, HP is mixed bulk. Same issues as the res bane. Makes quite difficult to use sustain builds (potentially even with summoner support) because aether/renewal will often have to activate at exactly the right time; she won't be able to survive an extra hit before it activates. She doesn't have much HP to begin with; a bane puts her into territory where average to good def and res just might not do it because her HP is so thin.
To look at some of the coveted IVs sets:
+spd -res: probably doesn't want to tank magic, especially blade tomes (by contrast, Nowi with 27 base res will probably survive one hit from even a green tome as long as its name doesn't mention Naga); might get OHKO'd by Nowi
+spd -HP: same, except without a superbane
+spd -def: probably best for general purposes. That's one IV possibility out of 21 (including neutral) on a seasonal unit.
+atk -any: the chill spd line is hard to use unless the emblem team has no defensive buffs, and even then positioning becomes an issue because she might need all three buffs, which isn't actually that easy, so she probably needs QR if she wants to be certain of a double against the fastest threats.
What if she had the absolute worst IV set you could get? I'd say -spd is definitely her worst bane and atk is not the worst boon among good ones.
-spd +res: generalist tank with QR, plain and simple. Still doubles most dragons if necessary with flier buffs, especially when dumping spd on dragons is so popular.
-spd +def: 38 def before skills should speak for itself, and she can still block doubles using emblem buffs.
-spd +HP: probably the worst IV combination she can have of 21 possibilities. DC+QR+Iote's shield still works, and the extra HP is good for trying to sustain using aether.
If she can work with these last IV combinations, what can't she work with?