>>31217744102 is a magic number. Base 100 is about as high as speed stats for things that aren't pure speed go. Anything faster than Chomp either has paper defenses, or negative offensive presence, or has mediocre both. On the other hand. This means that most anything that would threaten Chomp has to survive getting hit by chomp, possibly twice if it is switched in.
The rest of Chomp's BST means that it isn't weak or squishy. It's bulk isn't stellar, but it is adequate enough that the only thing faster than Chomp that Chomp really needs to worry about is Weavile.
Chomp's Speed is also great in that with a scarf, it generally outspeeds all mons who would generally run a scarf over a band or specs, similarly outspeeds things at +1 speed (DDance Mega Zard/Salamence, ect), and even stands a decent chance of outrunning a lot of pokemon who would even need to buff to +2 speed.
TL;DR: Garchomp is JUST faster than anything that isn't just a ball of speed.
