My apologies, but I wasn't really trying or intending to argue; it's more of "those two are great moves you can't really ignore" type of thing. Even with the abdundance of Max Elixers in the game (which does make that PP thing I said useless tbh), sometimes, especially against bosses with Pressure (or bosses in general), you don't really have the time to make use of the item 24/7. I think you're underestimating Thunder Wave a bit; I'd use it over a Sleep Seed / sleep-inducing move simply because it /usually/ lasts longer. While sleep's effects may vary, there have been many times that the chance to use an item or use attacks have been wasted, as it can wake up a turn later. Also, Thunder Wave as a TM isn't that common besides Amp Plains and finding it occasionally in Kecleon's Shop.
Regarding Shinx's great offensive presence, I'm not too big of a fan on Aggressor, (and Counter Basher if used together) because of the defense drop. Ik, it isn't /that/ much alone, but I have used Shinx and Riolu often, and the fact that a neutral attack causes so much damage to them (especially against Pokemon their typing is weak against; Flying for Riolu and Nidoqueen for Shinx) disappointed me. It's kind of a double-edged sword: you hit really hard, but when hit, it takes a lot more damage than desired.
In terms of offense in general, I'd definitely give the point to Shinx, but even with the natural moves it can learn (Crunch), TMs exist too, giving Pikachu some differing attacks besides Electric. Also, Thunderbolt is learned before Discharge for Pikachu, so it DOES have usefulness besides extra PP, as it can act as a semi-Discharge attack.