Not if they're capped at 25 kilometers per hour.

Yes, they're now. Those laws existed for much longer within Germany already though, hence why I compared them.

It is plenty, as long as the torque is sufficient. When mountainbiking I have never felt I would need more power, even on climbs where keeping the front wheel down is tricky. Of course you cannot sustain 25 km/h on steeper hills, but do you even need to?

250W is the EU's legal limit for continuous power, measured by its heat output over a 30 minute test. So with better cooling you can legally build stronger motors.
My pedelec has a motor that can output 600W, yet is perfectly legal and EU certified.

Start by printing this and keeping it with you. Then dig around until you can find the specific federal regulation and regulations pertinent to your state, print those out, too.

I used to do motorized bicycles, got pulled over with a friend once. Cop was all "You have to have registration and insurance and and and." I said, "Wait, I have the Illinois law on my phone here, this went into effect Jan 1 this year [I forget now what year that was]." Cop took the info back to his car for a few minutes (in the meantime, I was putting my chain back on, it had fallen off). He comes back and says, "I learned something new today. Be safe."

Told him we had our route planned out to avoid the high traffic roads already, that we always followed the rules of the road for cars and bicycles. I'm sure it didn't hurt that we were both wearing full face helmets and armored jackets.

Cops are very frequently ignorant of the actual law:

Class 1 ebikes: 

These ebikes are limited to a maximum speed of 20 mph and are designed to operate solely on pedal assist. They do not have a throttle for motor power.

Class 2 ebikes: 

Similar to Class 1, these ebikes also have a maximum speed of 20 mph. However, they are equipped with a throttle in addition to pedal assist, allowing the motor to operate without pedaling.

Class 3 ebikes: 

These ebikes are restricted to pedal-assist like Class 1 but can reach a higher maximum assisted speed of 28 mph.

The above are not motor vehicles in any state. If a cop challenges you on it, you can try to explain and encourage them to look it up but if you get ticketed it won't stand up in court. Feel free to talk to a lawyer in your area to confirm of course, don't take legal advice from strangers on the Internet: Verify information for yourself.

What? Why wouldn't you ride ebikes on bike trails? That's the whole reason I bought one lol

Thats because the added weight and power tears up trails, and the stewards hate that shit.