Is it possible to have a strong scout?

Your Question seems kinda weird, but I will try to answer it.

1. Is it possible to have a strong scout?
   

Yes, there are a lot of strong Light Tanks, f.e. the Russian T 100LT or the French EBR 105.

2. Is it possible to have a scout that can take on a tank-destroyer for power of shell?
   

No, and that's for good reason. Tank Destroyers are meant to have good guns and high damage potential. Light Tanks are basically the exact opposite of that, they are meant to be stealthy, fast, small. Light Tanks are not made to deal damage in the first place, they are made to scout the enemy Tanks, so that your team can kill them. Wargaming purposely put weak guns on Light Tanks because they don't want them to be overpowered. If Light Tanks had similar guns compared to Tank Destroyers, why even play TD's?

To summarize:

There are a ton of strong Light Tanks in the game, but none have actual TD guns. A Light Tank is strong if it hast good mobility, camo, view range, and a decent LT gun.
Light Tanks are probably the hardest class to play in the game, so if you are new, you should learn the game first by playing easier tanks like Tank Destroyers or Heavy Tanks.
Light Tanks are played to scout the enemy team and farm spotting damage instead of causing damage by yourself. They are mainly to support your team but are very strong if you are a good player, they can deal damage by themselves but not as well as a TD.

Some examples for good Light Tanks:

1. Chinese Type 64 (Premium Tank at tier VI)
2. French EBR 105 (Tech tree Tank at tier X)
3. German HWK 30 (Premium Tank at tier VIII)

WOT has different classes of tanks with different strengths and weaknesses.

See WOT-Homepage - Vehicle types and functions

Tank destroyers(TD) have a heavy hitting and accurate gun and good front armor and a good angle to make projectiles bounce. In their back, they've got weak armor. They're far less agile in terms of turning and driving.

Because of that, a scout can simply drive bedind a TD and shoot in its weak spots on its back. Moreover, with broken tracks most TDs are easy fodder for all other tanks.

Short description:

Heavy:

• Heavy armor
• few weak spots
• good gun
• slow moving/turning

Medium:

• moderate gun
• moderate armor (all sides)
• moderate speed
• depends a lot on the tank itself

Light (Scouts):

• fast and agile
• low or medium gun
• no armor
• pretty good spotting abilities

Tank Destroyers:

• good gun
• good front armor
• weak side and back armor
• slow, not agile

Self Propelled Guns (SPG):

• good gun
• can shoot over obstacles
• bad manueverability
• pretty slow
• no armor

Take care as each tank has its own properties. You got mobile TDs with no armor, you got immobile heavy TDs, see T28 vs Hellcat.

Basically, it's a game of rock paper scissors: Heavy > Medium > Light > TD > Heavy with SPGs being a special case.

WOT depends heavily on strategic movements and knowing enemies weak spots. A new player with a T10 Maus(pretty much unkillable) can die to experienced T8 players that know its weak spots.

Feel free to edit my answer and correct it, I didn't play WOT for over 2 years now.