1. Trevor isn't too bad of a card; it's decent if you are in a tight pinch. But the issue comes in it being a Supporter, and as you know only one Supporter can be played per turn. Since there is no limit to Item cards per turn, it's usually better to search for a Pokemon using one of them, such as any of the Balls (Ultra Ball, Great Ball, Poke Ball, Repeat Ball, etc.). That way you can still play a useful Supporter the same turn.
Some Item cards that will let you find a Pokemon include things like above-mentioned Balls, Evosoda (search for an Evolution), and Revive (from discard to bench). If you are playing in Extended format, you have Super Rod, Pokemon Communication, and additional Balls like Heavy Ball and Level Ball (though this one is getting a reprint soon!).
Sometimes even using Call for Family Pokemon is a better bet, especially in the early-game.
If you absolutely must use a Supporter for your Pokemon-searching needs, Wally would probably be a better one to use than Trevor, since it allows first-turn and same-turn Evolution. Also Pokemon Fan Club allows you to draw two Pokemon instead of one, but it's to the bench instead of to the hand.
2. Night March is a tough fight these days now that Trump Card is banned. The best luck I've had is in picking off the benched Night Marchers ASAP by using Lysandre or bench-attacking Pokemon. Also making their energy flow difficult helps, by using Enhanced Hammer (since they like sticking DCE on Mew) and making sure you have Stadiums to counter their Dimension Valley.
It'll also help us to give advice for the Night March matchup if you could tell us which deck(s) you're fighting it with. :3
