Gandalf the White could see play in legend-heavy Commander decks with white mana as a support card, but on the whole, legendary flash isn't a strong enough effect for Gandalf the White to be a viable Commander
You can take a Hardened Scales route to stack up counters faster, or focus on modified payoffs like Kodama of the West Tree and Akki Battle Squad
In most cases, this means Curie copies exactly what was printed on the original creature and nothing else, plus the additional ability
But as it turns out, FDN Collector Boosters have enough premium versions to keep its Collector Booster Display's price up
This could be through blacks removal, reds direct damage, or blues bounces and counterspells
This is obviously very strong with multicolor decks