When you decide to buy 3 variants to unlock the elite/master tiers champ mechs don't count as a separate variant but Hero mechs do.
Case in point I love the Kintaro 18 and have the 18 and 18C, they only count as one variant the 18, while a Golden Boy is an 18C with one additional laser hardpoint, it does count as a separate variant.
I guess the logic is you can build an 18 into an 18C but not into a Golden Boy.
There is an upside, if you don't care about elite or master and really like a variant with a champ or love the champ variant and want 2, the basic tier will already be unlocked for it to the point you have the first one. Same applies if you already have 3 and are unlocked to master tier.
Edited by Tractor Joe, 22 March 2015 - 06:42 AM.