1985 - With G.I.Joe popularity exploding, 1985 saw the biggest expansion in the toy line to date with 28 figures. It included 21 carded characters, 6 vehicle drivers, and 1 mail-in figure (Sgt. Slaughter). All of the figures were new characters, except for one, which was the Snake Eyes (v2) release with a new uniform and his wolf, Timber. While Timber appeared in the cartoon back in the first mini-series in 1983, he did not appear as a toy until 2 years later.
1985 marks the first real season of the animated series. While the 1983 mini-series (The Mass Device) and the 1984 mini-series (The Revenge of Cobra) are considered by many to be parts of the first season, they only amounted to a combined 10 episodes. 5 episodes a year is hardly a season, and a season does not typically span the course of 3 years. So it would probably be much more accurate to consider them mini-series that came before Season 1. So, what's this have to do with the toy line? In 1985, the show moved from a mini-series format to a genuine afternoon cartoon program, releasing a staggering 55 episodes. To put it simply, there were 11 times more episodes released in 1985 than in 1983 or 1984, and these episodes aired daily in a regular time slot versus the mini-series airing sporadically. The impact that this exposure had on the toy-buying 80s youth was tremendous. A production/design detail to note is Hasbro started scaling down the amount of G.I.Joe figures with removable helmets. In this 1985 line, there are only 3 figures with removable helmets: Crankcase, Footloose, and Bazooka, which is only 10.7% of 1985 figures. In 1982, 10 of 16 figures came with removable helmets, which is 62.5% of 1982 figures. To put it another way, 6 times more of the figures released in 1982 had removable helmets than in 1985. The reasoning for this has not been confirmed, but one can reasonably assume that having helmets as part of the head mold were much cheaper than having a separate, removable helmet, which also would require painting hair across the top of the figure's head.