Time to see people rage quit due to this one card. Many broken high level monsters can't be summoned at all. Goodbye blue eyes, goodbye despacito, goodbye lightsworn.
Despacito is summoned following its own effect activation, so Roach cannot negate it. Blue-Eyes summoned through White Stone is safe either. Roach only stops Fusion/Synchro summons and inherent special summons like Levianeer and Alternative White.
Yes it is. Roach cannot negate special summons that starts a chain link, and stone's effect certainly does. Try negating the summoning of BEWD through stone and you'll find out if you can negate that.
Fusion/Ritual summon(s) cannot be negated using the ROACH. The fusion/ritual monster is being summoned by a card effect,starting a chain,so Roach cannot activate during the resolution of the card effect!! Counter traps/monster effects that negate summon(s) cannot negate a summon performed by card effects! But you can prevent a monster(s) from being summoned by negating the card itself that summon!