I would say 2015 was the year of the Gyarados, it brought forth 18 new Gyarados cards from English and Japanese sets, including the first EX revival in 11 years since Flight of Legends in 2004
There was major hype over these cards and a lot of involvement from this community specifically. I’d say this is one of the top things that gained our attention.
I’m not showing off for this one - just thought it was a cool development for my own collection. The Chinese EX Legend Maker set was unearthed fully, and even graded. Maybe not notable for most, but it was for me!