Is any particle allowed within the laws of physics? In the same way wormholes are possible but not guaranteed to occur naturally, is a theoretical particle possible such as one with a mass of a tonne and a charge of -3, or are there upper and lower limits of a particle's properties?
Related: Is there a theoretical upper bound on the mass any new particles can have?
 A: I'm not sure I understand what you mean by lower bounds, since there are massless, and also chargeless particles, like the photon. Let's stick to upper bounds.
When it comes to charge, hadronic resonances have some pretty high charges like 2, and nuclei go on and on... Don't get started on elementary versus composite.
A droplet of strange matter could be pretty big. But, no, you want elementary?
A very heavy particle would be so unstable to decay it would be hardly detectable, unless it didn't much couple to our world, in which case it would be a cosmological entity...
In any case, if you are talking about 1000 kg, so, then, 11 orders of magnitude higher than the Planck mass (2.176434(24)×$10^{−8}$ kg),  its Compton wavelength would be $10^{-21}$ smaller than its Schwarzschild radius, so it would qualify as a mini-black-hole, rather than a quantum particle. Can you compute this?
Most people appreciate small/pointlike objects   heavier than the Planck mass are easier to think of as black holes than as particles.
