Tremolator from Sound Toys is a native plug-in that emulates the tremolo effect of classic guitar amps such as the Fender, and even the great tremolo sound of the Wurlitzer electric piano. The company analyzed the waveforms created by some of their favorite old gear, and using their custom LFO waveshape editor built into Tremolator, perfectly recreated them.
The plug-in adds dynamic control of speed and depth that lets the tremolo respond to the source, and also adds MIDI sync to lock to the session's tempo. A programmable Rhythm Editor let's you write custom patterns and turns this tremolo into a rhythmic auto-gate. This allows the user to switch the nice smooth tremolo waveforms over to a sharp square wave and turn the plug-in into an auto-gate.
You can lock it to MIDI with the flip of a switch, then select 1/8th notes, 16th notes or whatever fits the rhythm you need. If "straight note pulses" isn't what you need, use the Rhythm Editor to write your groove. Add some swing or shuffle, accents, and analog mode and use the Waveshape Editor to tighten or loosen the gate time.
The Tweak menu contains the Dynamics controls, parameters that let your playing control the speed and/or depth of the modulation. You can create cool speed-ups or slow-downs based on how loud or soft you play. You can create smooth increases in depth as your cords fade out, or heavy tremolo that fades away. Plus there are already some great presets in the Dynamics folder that you can "tweak" to fit your needs.