easy alt/rock/punk/poppunk bass songs?

I am a guitarist, lead guitarist in my band, I play Classic Rock, so, Led Zeppelin, The Who etc. So from experience, almost all bass songs are easy.

Jealous Sound - Hope for Us

You should learn music theory (http://www.amazon.com/Leonard-Bass-Method-Easy---Use/dp/0793563836/ref=sr_1_1?ie=UTF8&qid=1368143088&sr=8-1&keywords=hal+leonard+bass+books) It honestly helps A LOT,and you get to learn how to read music and it helps train your ears..You can teach yourself this,even if you don't know a single thing about theory! anyways back to your question.

The Strokes-Juicebox,Alone Together,Someday,Take It Or Leave It,New York City Cops(Level:Very Easy)
Queen-Bohemian Rhapsody (Medium)
Led Zeppelin-Dancing Days,Whole Lotta Love (Easy)
Misfits-Hybrid Moments( Easy and the bass is SUPER audible)
Weezer-Say It Aint So and Only In Dreams (Both easy,but are in D# Tuning,so make sure your bass is tuned correctly)
The Beatles-Something (Easy)
Anything by Joy Division is easy
Anything by The Arctic Monkeys

You should use these tools to tune yourself http://www.get-tuned.com/online_bass_guitar_tuner.php
And this metronome,in case you want to play some rhythm parts http://www.metronomeonline.com/