Hey there. Your moveset is not that bad, and rather than suggest a completely new one probably suited to the metagame, I'll just give you a few tips to get the most bang from your buck.
Just a slight note: you'll find that the type-based items (Magnet, Nevermeltice, Black Belt et al) are not really effective, and that there are many better held items out there. Thus I would go with Leftovers (in this case).
Naive and Rash are both natures that decrease Sp.Def, as you probably already know. It is clear why you chose these - Raichu has no special-based weakenesses, and Sp.Atk or Speed are better stats to be boosted. The nature you choose is really up to you... do you want a quicker Raichu or one that packs one helluva Thunderbolt?
EV-wise, you should look towards your chosen nature. If you went with Naive, then pool 252 EVs into Speed. That'll ensure you can outspeed pretty much any Pokemon you'll face (wild or otherwise), as well as help you out
should you opt to battle anybody competitively. The rest can be spread between Sp.Atk and Atk as you see fit. If you wanted a more damage-dealing Raichu, and thus chose Rash, then 252 EVs in Sp.Atk should make sure you're doing maximum damage.
Moveset-wise, well it's not too bad. Perhaps a tad too attack-based, but thats okay:
-Thunderbolt is an obvious choice. Powerful, 100% accurate, STAB... it HAS to be on Raichu's moveset.
-Reversal is always good if you expect Raichu to take alot of damage (which it does). Of course this may not go too well with Leftovers, as you'll find your health slowly recovering and Reversal's damage output dropping consequently. Still it's a valid choice and summat unexpected in competitive battling.
-Mega Punch just isn't worth it. I would go for Return if anything.
-Rollout... meh. I know the damage output increases per turn (much like Fury Cutter), but I think there are better moves available.
If you DO want a moveset that can be used ingame, as well as proving effective in competitive battling and the metagame, then try this website:
http://www.smogon.com/advance/raichu/strategy
The three stated sets are obviously geared towards the metagame (as you shouldn't be facing Blissey et al ingame), but movesets such as the first (T'bolt, Surf, Sub, Focus Punch) are great and really effective both ingame and out.
Anyway, good luck with your Raichu, and let us know what you do decide on.
