One of the best things about Tony Hawk's Pro Skater 1 + 2 is that it feels very old school in its content. Not only do you have the time trial objectives to contend with, but there are a bunch of collectibles that let you uncover additional secrets.
A set of alien plush toys is one of them, and collecting them all while walking through them will unlock one of the coolest costumes in the game in the form of Roswell Alien. It takes a bit of work to find them as there is one hidden in every level of the game.
Fortunately, most of them are in places that are easy to access, so it won't be too difficult to get your alien skateboard to play. Here are all of Tony Hawk's Pro Skater 1 + 2 snug locations.
Warehouse
Going down the ramp and entering the warehouse, turn sharply left to where the ramp is and head over it, to the top quarter pipe. At the top of here you will see the plush toy in the upper right corner of the ramp.
School
From the start of the race, go right where you will find a small grassy area covered in shade. It's not easy to spot, but the plush will be hidden in the corner. Run around the corner to crush him.
Mall
Once you've completed the coffee grind spreader rail, head down the ramp, but stop when you reach the bottom and take a sharp right turn. Next to a door with a parking sign above, there should be a stuffed animal tucked away in the corner.
Skatepark
Once you appear in the level, stop and turn around to where the judges are placed. Above them you'll see a stat point, but if you walk towards it you'll also find a stuffed animal hidden near the steel beam.
Downtown
Climb to the roofs using the large vehicle transporter, where you will then reach the roof via a curved stairwell. Once there, you should see the wooden bowl. Enter here, and if you head to the far right with the corner of the triangle, it will be hidden on the outer side of the bowl.
Jam descent
No downhill interference is necessary here. If you just turn around at the spawn point, you'll spot the little alien plush in the right corner.
Burnside
This one is between the concrete supports as you look up. You will need to head to the ramp under the triangular concrete space and pass through it. If you hit it correctly, you will crush the alien when landing.
Streets
The plush here will be behind the sign above the store which has an American flag hanging from it. It is also identifiable by the glass room with the checkered floor.
Roswell
This little dude is in the secret room of the bowl which contains the flying saucer and the tank. When you enter, the plush should be behind the door at the top of the bowl.
The hanger
In the secret outdoor space with the videotape accessed by crushing the helicopter blades, if you take a left on entering, the plush will be hidden in the corner around the snow.
School 2
Once the race has started, go down to the right which leads to a large courtyard. You should see a green awning with a stat dot on it. Use the lockers to then ollie on it and the plush will be in the alcove.
Marseille
Walk past graffiti covered transitions until you reach a grassy wall with a small section covered. Wall grind on this, and it should open up a small area that leads to a crypt. In this section, a plush will sit on a small raised concrete platform in the corner. You'll have to be quick for this one as you'll only have 60 seconds to grab it.
NY City
The game will highlight the 50-50 Joey's Sculpture challenge for you, and here is where you need to head. Underneath is a quarter pipe that you can ride. On the other side is a soft toy sitting on the floor.
venice beach
Near the concrete bowls is a wooden boardwalk at the edge of the map. If you follow this, doing your best to avoid the sand, you will eventually come to a concrete neighborhood. Between that and a wall, there will be a stuffed animal hidden here.
Skatestreet
This one is one of the hardest to reach in the game. First of all, you have to grind one of the hanging rails to open the secret outer area. Go around the corner and you'll find two quarter-pipes with a big gap between them. If you go up the pipe to the right towards the wall, you will see a very thin platform to land on. As you look up there you will see a plush sitting on the wall. You need to have the right angle to land on the wall and then roll onto the plush.
cream philadelphia
First of all, grind the telephone wires as this will give you access to the area under the freeway. Make your way to the makeshift wooden half-pipe and behind there will be a plush under the steps. This one is easy to miss with the wrong lightning bolt, so be careful.
The arenas
On the raised outer ring of the arena, follow the wall and the plush should be next to the curved ramp that leads to the middle section of the arena.
Chopper Drop
This one should be pretty easy to find as it's on the platform at the entrance to the huge half pipe.
Skate Heaven
To unlock Skate Heaven you will first need to have completed all of the Tony Hawk's Pro Skater 2 tour objectives. After that you can head to the level and activate the volcano first by grinding the space on the rail at the neon blue. Then you have to take a leap of faith in the volcano using one of the nearby halfpipes to gain speed. Once through, you will be transported to a secret location. From there, stay to the left and you should come across a wooden quarter pipe that the last plush will sit on.
Once done, head to the main menu and then the challenges tab. Here you will find the Roswell Alien ready to be chosen. Choosing it gives you full stats on everything, for those looking to get a little crazier in the game.