Let's compare shall we?
Forre is type of wall, or a defensive Hazard setter and spinner. It sets Stealth rock, spikes ect: then uses Rapid spin to spin away the Hazards that you opponent has already set. It's fame comes from it being the only Pokemon to learn all 3 types of Hazards and Rapid spin. This makes it very versatile. It's high defence also makes it very easy to shrug of many Physical hits from a range of Pokemon. As well as being a good dragon counter that lacks Fire moves. Their are a range of sets but most of them are very similar. I like using this one...
Spinny Thing (Forretress) @ Custap Berry
Evs: 252 HP / 252 Def / 4 SAtk
- Stealth Rocks
- Spikes / Toxic Spikes
- Rapid Spin
- Volt Switch
This is the set I run and I find it to be quite effective.
Scizor is a very powerful sweeper. It's has just one weakness like Forre, but instead of Hazard setting and spinning, it abuses it's high Attack power in combination with it's powerful technician ability to boost the power of it's STAB priority Bullet punch. I mean, why wouldn't you want an extremely powerful move that always goes first? All moves of 60 Base power or less gets a large boost in power, then STAB on top of that. Choice Band can and often is used to Max the power to absolutely ridiculous levels. This is my Band set.
Scizornician (Scizor) @ Choice Band
EVs: 252 Atk / 252 HP / 4 Spe
- Bullet Punch
- Bug Bite
I hope I helped ;D