in FF III you also have a four member party with a similar feel and just like in bravely default, each character can have any job. the jobs are completely changeable too.

there is no main series FF and thus, no spin off. just look at logic.

It's a spin-off, just like Mystery Dungeon is spin-off in the Pokémon series. There is a reason why every roman numbered FF game is treated with more money.

mystery dungeon doesn't follow the story or the gameplay of the main series and that makes it a spin off. final fantasy's numbered games doesn't follow the same story or gameplay mechanics = it doesn't have a main series. that means no final fantasy is a spin off.

Not directly but it does fall in line with the traditional, game play and job class heavy Final Fantasy game that you in different Final Fantasy incarnations, such as the more direct 4 Heroes of Light, FF Tactics, FFV, etc. But directly off Final Fantasy 3, I'd have to play it myself to confirm but I somehow doubt that to be the case.

I believe its from the same team that worked on the FF3 remake for DS and FF The 4 heroes of light for DS aswell.
Those games and Bravely default all seem to share similarities, though hopefully the story is better on Bravely than the other 2 titles that were very light on plot.

Yes it is a spin-off.

So you are saying Crystal bearers's is a mainline game, you are saying that FF Tactics is a mainline game.

The numbered Final Fantasies are the main series, simply because of they started the series, they have the biggest budget and the numbering system.

there's nothing tying the "main series" together. different stories and different gameplay mechanics. there is no main series.

Waht's tying them together is the numeral system. The rest are spin-offs as they hold the name FF for the sake of holding it.

I think i almost lost some iq points after reading this. you are proving there is nothing tying them together.