I'll elaborate a bit on their effects.
Spikes
- can stack up to three times
- at 1 layer they remove 1/8 of the opponent's health
- at 2 layers they remove 1/6 of the opponent's health
- at 3 layers they remove 1/4 of the opponent's health
- does not affect Flying-types, Pokémon with Levitate, those holding Air Balloon, or those under
the effect of Magnet Rise or Telekenesis ("Raised" Pokémon)
- Pokémon with Magic Guard are not hurt by Spikes
Toxic Spikes
- can stack up to two times
- at 1 layer they will Poison the opponent
- at 2 layers they will Badly Poison the opponent (a la Toxic)
- do not affect Raised Pokémon, as well as Poison- and Steel-type Pokémon, and those with the ability Immunity
- Pokémon with Magic Guard are not damaged by status inflicted by Toxic Spikes (however they are still Poisoned)
- if a Poison-type switches into Toxic Spikes they are removed from play
Stealth Rock
- cannot be stacked
- deals damage based on how weak the opponent is to Rock-type attacks
- full information here
- Pokémon with Magic Guard are not damaged by Stealth Rock
Sticky Web
- cannot be stacked
- lowers the opponent's Speed upon switching in by 1 stage
- does not affect Raised Pokémon
- Pokémon with White Smoke or Clear Body do not have their Speed lowered
- Pokémon with Contrary have their Speed boosted; Pokémon with Simple have it lowered 2 stages
- Sticky Web will activate Defiant and Competitive
Sources: The move's respective Bulbapedia and DB links, as well as experience
