How about a spider tank? slow and steady but hard to kill.

Hmm...I like the idea but how would he look like? Like in a toy tank? Now that I wrote it it does sound kinda cool XD

I was thinking that he could have chunky metal legs and a metal body with an explosive tank gun on the top that is his offensive weapon.. To balance it out he is slow at turning to aim and has a slow(ish) fire mode that is explosive but deals a small to moderate amount of area of effect damage, but a direct hit from the smallish missile will take most (or all) of your health.

BTW if you are having a secondary fire mode he could have a machine gun too or swap them around to the tank gun being the secondary.

I am a huge fan of spiders and know a decent amount about some spiders, and seeing the power ups and some vehicles it gave me some ideas so I thought I should mention them

instead of a paper boat vehicle how about a water spider: http://www.arkive.org/water-spider/argyroneta-aquatica/image-A12754.html

instead of the pilot spider it could be a jumping spider: http://boredomtherapy.com/spider-vision/

instead of the spartan spider it could be a bird eating spider: https://www.smithsonianmag.com/travel/where-see-worlds-biggest-spiders-180960938/

instead of a gunner spider it could be a Scytodidae spider: http://www.spiders.us/image/scytodes-thoracica-4/

and for the toilet paper spider it can be a Rolling Sahara spider: https://www.youtube.com/watch?v=bsnNmChDXAc

and the idea of a tank spider should be a wolf spider that shoots its eggs (and they have thousands so it should not do a lot of damage but can shoot rapidly [kinda like the heavy from team fortress 2]): http://www.pestworld.org/pest-guide/spiders/wolf-spiders/

Thanks for reading and I hope you enjoy!