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