The game is Chest Deep and set in Anchorage, Alaska. This particular Trickster has set himself up as Anchorage's Information Broker; if anything is happening in town, I want this character to know about it or have to means to find out.
Thats basically what the following skills are for: Lore, Scholarship, Contacts
Add a stunt or two to increase said skills when used for something concerning the town.
[...] I plan on doing lots of shapeshifting
The usual shapeshifter power set would work just fine.
Echoes of the Beast
Beast Change
Human Form
Spider Walk
Claws
Inhuman Strength
Inhuman Speed
Maybe a Toughness power ??
The powers may of course vary depending on how much refresh you have to spend.
and prankster actions;
Deceit and/or Performance Skill
Maybe another stunt or two to supplement the skills.
Ok, you won't bve able to take all those powers and stunts when working with Chest deep.
If you want him to be a Trickster first and then a shapeshifter, you'll need some stunts to supplement the skills.
If you want him to be the Shifter first, don't bother with the stunts. Put the trickster skills high up in the pyramid in the normal Human form, and reduce them as needed when shifted.
You should also consider one or two Aspects that denote his status as Information Broker and Trickster.