Hmm.
It’s… kind of an all-or-nothing tactic? Like, in theory, a Stantler with a Focus Sash can kill absolutely anything with this move, barring entry hazards, weather damage and multi-hit attacks, which strikes me as a terrible thing to give to any Pokémon. The smart thing for the opponent to do is always to switch out against Stantler until it runs out of Doom Bell PP – which means that the smart thing for Stantler to do is never actually to use Doom Bell, and instead to exploit the fact that very few Pokémon will willingly stay in against it by spamming Calm Mind or Thunder Wave. You get this irritating game of chicken, where Stantler is daring an opponent to stay in, try to kill him, and risk being Doom Belled, and the opponent is daring Stantler to use Doom Bell and risk running out of PP for it without killing anything. Worse, it’s clearly a very good idea for Stantler with this move to have Substitute as well – so the opponent is in a situation where they can either switch out and risk letting Stantler set up a free Substitute, making him even more annoying to deal with, or not switch out and risk instant death. I actually think a lot of Stantler might wind up not having Doom Bell at all – just something along the lines of [Calm Mind | Psyshock | Thunderbolt | Substitute/Energy Ball], keeping one of the attacks secret until very late in the game, and just exploiting the fear of the possibility of Doom Bell, since optimal tactics for the damn thing involve not using it. I’m… not convinced it’s a good idea.
If it’s any consolation, Stantler’s not… that bad. His movepool is solid and he has two great abilities; his stats are just a bit lacklustre.
Also… why a bell? As far as I know Stantler doesn’t have any sonic powers or any flavour related to bells or ringing… he doesn’t even learn Heal Bell.
Pokémaniacal 