What I learned against FG roll "spammers"

One thing I realised when facing a roll spammer that helped me greatly deal with them : Roll don't damage you.
It goes without saying, then it will go even better if we say it, what hits you is the punish after you commmited.
The solution ? Do not freak out. Stay calm to not throw autopiloted attacks. (in any and every situation you should aim to keep calm)
Then, safe options (jabs, aerials [usually autocanceled], certain tilts and even smashes [like MK's Fsmash]) so your opponent doesn't get the opportunity to punish
If you notice a pattern in the defensive spam, you can play around him (but be correctly timed). For instance, overshooting dash attack will clip backroll and be safe to forward roll. Pit's retreating Nair/Dair will be safe on spotdodge/shield and clip his forward roll.

If the opponent is not willing to approach you should not feel forced to approach if you have the lead. If your character has a decent projectile and you can outcamp him. You can also walk. Walking will give you stage control for free because it doesn't remove an options unlike running or jumping.