Dawn anime viewing guide:
Intoduction (001-003)
Best arcs:
Maylene Gym battle (066-068)
Wallace cup intro (075-076), Wallace cup (077-079)
Sinnoh Grand Festival (174-178)
Notable contests:
Zoey intro 011-012. Kenny intro 026-027. Loss streak 049, 061. Against her mom's rival 095. Ursula 114, 161, 162.
Mamoswine's arc 84, 104, 106, 119.
Fun Dawn fillers: 010, 022, 029, 035, 062, 086, 124, 155, 164, 167, 171
If you want some pearlshipping watch the Johto arc, 133, 154, Darkrai and Arceus movies
She is also great in other arcs like the Tag Battle Competition, Galactic, Summer camp and lots more but this is the essential.