No you don`t have to use the poke-radar to catch lavitar.
You can't you must have the pokeradar and the national pokedex.
evolve it from pupitar which you need to evolve from larvitar which is a pokeradar Pokemon on route 207
first you need a pokeradar & max repel than you go to route207 en use a max repel en the pokeradar en you receive a larvitar 10%
You can't know when it is Larvitar. But, at my research i have found it that a Larvitar appears 2 of 10 times you radar on.
you can catch larvitar in route 207 north of oreburgh (diamond only) using the pokeradar, 22% chance of getting it larvitar( at lvl 6-7) look for the rustling grass that's shiny after using the pokeradar; it might sound dumb but it works as i caught mine on the first try.
Larvitar can be found in Mt.Silver.
I got mine as a daily Pokemon from dawn's sister in sandgem town but im pretty sure you can use a pokeradar on route 207 about oreburgh.
ONLY ON POKEMON DIAMOND, PEARL DOES NOT HAVE LARVITAR, PUPITAR OR TYRANITAR!Larvitar is very rare so it may take a while to catch. You need to go to Route 207. This is just above Oreburgh City. You need to use a pokeradar. You get this from the Pal Park (you need to have completed National Dex). At Route 207, use the pokeradar. When the grass rustles, walk into it. This may be larvitar, or just a normal Sinnoh pokemon. Be prepared to be very patient!Hope everyone found this helpful, written by lushbob
You can only catch one on route 216 with the PokeRadar in a swarm. You can see what Pokemon are swarming on a particular day by talking to Dawn/Lucas' younger sister at their house in Sandgem.
You can get a Larvitar on Pokemon Diamond by using the Pokeradar on Route 207. If you're using Pokemon Pearl, you'll need to trade with Diamond.
you can catch a larvitar on route 206 if dawns sister says you can.
to find larvitar go to the Seavault Canyon