Here is the full list of all 36 Tony Hawk's Pro Skater 1 + 2 achievements worth 1,000 gamerscore.
Reach Career level 100.
Complete all "Hard" Get-Theres.
Earn 5,000,000 points in Trick Attack across all playtime.
Complete all Gap collections.
Place 500 objects in CAP.
Earn 2,000,000 points in Combo Mambo across all playtime.
Paint 100 surfaces in Graffiti across all playtime.
Give 50 Letters in Horse.
Earn the "Legend" Challenge Collection.
Unlock Officer Dick.
Earn the "Veteran" Challenge Collection.
Create a new park and upload it.
Spend $10,000 in the Skate Shop.
Find every alien plushie.
Find all Stat points for any Pro Skater.
Get hit by a vehicle on every map that features them.
Complete every goal in THPS2 Classic and gain all gold medals.
Achieve a judge score of 99.9 on a competition run.
Complete every goal in THPS1 Classic and gain all gold medals.
Land a 1,000,000+ point combo.
Achieve a High Score of 1,000,000+ on any classic Park.
Achieve a High Score of 10,000,000+ on any classic Park.
Complete a match in multiplayer.
Get hit by the Bull in Bullring.
Unlock Bullring in THPS2 Classic.
Earn any 4 Medals on competition parks in Tours.
Bail a 100,000+ point combo.
Unlock School II in THPS2 Classic.
Unlock Roswell in THPS1 Classic.
Earn the "Rookie" Challenge Collection.
Reach Career level 10.
Break 20 Panes of Glass.
Create a skater using the CAS system.
Earn a Medal on any competition park in Tours.
Land a 50,000+ point combo.
Unlock School in THPS1 Classic.